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METAL- WORK 



A HANDBOOK FOR TEACHERS AND STUDENTS 



BY 

HUGH M. ADAM 

ORGANIZER AND INSTRUCTOR IN METAL-WORK, JARROW EDUCATION 

COMMITTEE; INSTRUCTOR, TEACHERS' TRAINING CLASSES^ 

DURHAM COUNTY COUNCIL 

AND 

JAMES H. EVANS, a.m.i.m.e. 

INSTRUCTOR IN METAL-WORK, TEACHERS' TRAINING CLASSES, ESSEX 

COUNTY COUNCIL; BRIGHTON SUMMER SCHOOL 

FOR EDUCATIONAL HANDWORK 



NEW YORK 

LONGMANS, GREEN, AND CO, 

LONDON: EDWARD ARNOLD 

1914 



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Printed in Great Britain . \ 



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PREFACE 

The subject-matter of this book is presented to the student 
accompanied by a word of warning : It is not to be considered 
as an exhaustive textbook on metal-work, but as an attempt 
to set down as clearly as possible an account of the equip- 
ment necessary, and of the operations and general principles 
involved in the use of metal- work as a method of education. 
No model courses of work are presented to be adopted whole- 
sale. The best courses are those determined by the varying 
conditions under which the teacher works, and which are 
evolved from the experiences and circumstances arising in the 
handicraft-room. 

The step from wood- work to metal- work in the handicraft- 
room is a natural one. This subject introduces the pupil to 
new conditions, new forces — at least, if not new, so disguised 
as to be unrecognizable— and consequently, to the necessity 
of adapting himself to his new environment, in order to meet 
by new methods the obstacles presented in the new material, 
tools, etc. His outlook is thus broadened and his nature 
receives a new discipline, in which process the attitude of 
mind created in the wood-work room will serve him well. 
This change of atmosphere revivifies his enthusiasm — a power- 
ful ally in the hands of the expert teacher. 

Metal-work has suffered considerably at the hands of the 
ill-informed. No doubt the term has led to erratic conclusions 
concerning its scope and objects, and to its being considered 
an unsuitable subject for the handicraft-room. 

But if we consider that the term " metal- work " includes 
the various processes involved, from the simplest wire, tin- 



vi PREFACE 

plate, sheet zinc, and copper work to the exacting demands of 
metal-turning and delicate repousse, we shall see that it 
admits of such convenient gradation as to render it eminently 
suitable as a school subject. 

As has been previously said, the pupil in the metal-work 
room is working under new conditions and employing different 
material and tools to meet his ends. 

In the wood-work shop certain laws had to be obeyed in the 
use of the materials and tools, and certain penalties followed 
the violation of these laws. It will be readily seen that 
increased vigilance is called for in the metal- work room on the 
part of both teacher and taught, for the penalties f c r the misuse 
of tools, fire, fluxes, etc., are more severe. Therefore strict 
obedience and curtailment of liberty are necessary until the 
pupil obtains that familiarity with his tools and materials 
which will justify a return to the freedom enjoyed in the 
wood- work lesson. 

The attainment of this familiarity with tools and processes 
will take up the greater part of the pupil's first year at metal- 
work. It is only then that he ought to be allowed to be the 
chief agent in determining to what purpose he shall apply the 
knowledge thus gained. 

At this stage a great demand is made upon the skilful 
teacher. He must be careful to co-operate with the pupil, and, 
without destroying the originality of any idea presented by 
him, so modify it as to make it practicable. A suggestion 
made by a pupil should neither be ignored nor allowed to pass 
without criticism. By a process of questioning, discussion, 
comparison, and consideration of conditions to be fulfilled by 
the object about to be made, the pupil can be led onward, and 
the content of his original idea increased. 

Much can be done in the metal-work room to add to the 
value of the teaching of other subjects in the curriculum. 
Many of the principles taught in the elementary science 
lesson are illustrated by the use of the various tools and pro- 
cesses employed in metal- work, and the pupil thus realizes the 



PREFACE vii 

practical use of being acquainted with them. Again, the 
actual making of models illustrating the principles of levers, 
pulleys, etc., and the construction of objects fulfilling given 
conditions of volume, etc., impress indelibly on his mind the 
truth of formulae and the value of accuracy, and give a 
practical application to his exercises in geometry. 

Metal-work, when combined with wood-work, considerably 
extends the scope of a boy's activities. If, in addition to his 
knowledge of wood- work, he is acquainted with the methods of 
working with wire, tinplate, zinc, sheet copper, etc., he is 
enabled to launch out on enterprises from which he was 
hitherto excluded. In many cases he will be better able by 
the use of both materials to fulfil the conditions demanded by 
many of his models in the wood-work class, and the result will 
be a more completely developed series of ideas. Care must be 
taken, however, that the circumstances do actually demand the 
use of both materials, and that each material, in its respective 
place, is the one best suited for the purpose, or the value of 
combined work will be greatly diminished. A few talks with 
the pupils, and the criticism of actual examples of combined 
work, both bad and good, will soon lead to an understanding 
of what is required. 

The respective merits of hand- and power-driven machinery 
in the metal-work room have often been a subject of con- 
tention. The chief argument against the inclusion of power 
is the large initial outlay involved in its installation, and the 
increased expense of upkeep. The chief argument in its 
favour is the fact that it allows the pupil to give his whole 
attention to the actual work in hand, without the distracting 
influences attendant upon driving the machine. On the 
other hand, the use of hand-driven plant calls for muscular 
control and increased general activity, and may therefore be 
considered of greater educational value. In the latter case the 
student is the sole directing power; he is brought into closer 
touch with the principles involved in his machinery, and with 
the action and interdependence of its component parts. 



viii PREFACE 

The fact that power plant is generally used in metal manu- 
factories is often advanced as a reason for its adoption in 
schools. This argument may be considered valid as regards 
the Technical School, where the aim is to fit the pupil for a 
definite career, but does it hold quite so strongly when the 
handicraft-room of the Elementary School is concerned ? 
Here we are dealing with the education of the child, and surely 
it is an important part of that education to allow the pupil to 
acquire those preliminary experiences which have made the 
modern machine possible. These are the questions which 
confront us, and towards which our attitude will of necessity 
differ according to the variations in the objects and the 
conditions of our work. 

The Authors desire to express their gratitude and thanks 
to Mr. Walter Smith, Principal of the Stanley Central School, 
London; Mr. W. H. Barker, B.Sc, Principal of the East 
Ham Technical College ; Mr. John Arrowsmith, Head-master of 
Mixenden Investigation School, Halifax; Mr. R. J. Mackie, 
Higher Grade School, Jarrow — for their assistance in reading 
the proofs, and for their help and encouragement at all 
times. Also to the following firms for the loan of blocks 
from their catalogues: Messrs. Pfiel and Co., St. John's Street, 
Clerkenwell; Messrs. S. Tyzack and Son, Old Street, Shore- 
ditch; Messrs. S. Parkinson and Son, Shipley, Yorks; Mr. H. 
Osborne, Westgate Road, Newcastle-on-Tyne ; Mr. M. Eadon, 
President Works, Sheffield; Messrs. A. Mathieson and Sons, 
Saracen Works, Glasgow; Messrs. Frazer, Chalmers and Co., 
Erith ; Messrs. Milnes, Ingleby Works, Bradford ; Messrs. 
Drummond Brothers, Guildford; Messrs. Buck and Hickman, 
Whitechapel, London; Messrs. Marplcs and Co., Sheffield; 
The Hardy Pick Company, Sheffield. And to the City and 
Guilds of London Institute, for permission to reprint their 
examination papers. 

H. M. A. 
J. H. E. 

June, 1914. 



CONTENTS 



PART I.— THE METALLURGY OF THE METALS USED 
IN THE HANDICRAFT -ROOM 

CHAPTER PAGE 

I. PROPERTIES OF METALS - - - . . 1 

II. OCCURRENCE OF THE METALS IN NATXIRE - - - 7 

III. MANUFACTURE OF CAST-IRON - - - - - 15 

IV. MANUFACTURE OF WROUGHT-IRON - - - - 23 
V. MANUFACTURE OF MILD-STEEL - - - - - 28 

VI. MANUFACTURE OF CAST-STEEL - - - - 39 

VII. THE ALLOY METALS AND THEIR MANUFACTURE — COPPER, LEAD, 
TIN, ZINC, ALUMINIUM - - - - 
VIII. ALLOYS -....- 
IX. WORKSHOP USES, PROPERTIES, AND CHARACTERISTICS, OF THE 

COMMON METALS - - - - - - 67 



46 

60 



PART II.— TOOLS AND PROCESSES 

X. VICES -------- 77 

XI. FILES, FILING, AND SCRAPING - - - - 84 
XII. MEASURING, TESTING, AND MARKING-OUT TOOLS - - 96 

Xni. SMALL HAND TOOLS ...--- 106 

XIV. SHEET METAL WORK, SOLDERING, AND BRAZING - - 125 

XV. FORGE WORK ---.--- 140 

XVI. DRILLING, RIVETING, PUNCHING, SHEARING, AND GRINDING - 157 

XVII. CASTING ...-.-- 171 

XVIII. LATHES AND LATHE WORK - - - - - 177 

XIX. REPOUSSi WORK, ENGRAVING, POLISHING, BRONZING, AND 

LACQUERING .------ 205 



CONTENTS 



PAET III.— WORKROOM EQUIPMENT, SCHEME OF 
WORK, AND TEACHING METHODS 

CHAPTER PAGE 
XX. SPEED, FEEDS, AND POWER, REQUIRED FOR MACHINE TOOLS, 

SHAFTS, ETC. - - - - - - -215 

XXI. STANDARD THREADS, BOLTS, AND GAUGES; SIZES AND PRICES 

OF MATERIAL ...... 219 

XXn. MOTIVE POWER ...... 230 

XXm. EQUIPMENT OF WORKROOM - - - - - 241 

XXIV. SCHEME OF WORK AS REGISTERED BY BOARD OF EXAMINATIONS 249 

XXV. SUGGESTIONS FOR COMBINED WORK IN WOOD AND METAL - 271 

XXVI. NOTES ON TEACHING METHODS - - - - 286 

XXVII. NOTES OF LESSONS AND USE OF BLACKBOARD - - 301 

APPENDIX: EXAMINATION PAPERS 

CITY AND GUILDS, 1913 ..... 309 

CITY AND GUILDS, 1914 - - - - - 319 

GLOSSARY ....... 330 

INDEX ....... 333 



FOREWORD 

By JOHN ARROWSMITH 

Principal of the Brighton Sumvier School for Educational IlandivorTc 
Head-vicLstcr of Mixenden Investigation School, Halifax 

The Authors of this book need not apologise for writing it. 
Metal-WorJc will be welcomed by many teachers and very 
many boys. Of books on wood-work in the handicraft-room 
there are more than enough for the present^ and I am glad to 
see that Messrs. Adam and Evans^ two old colleagues of mine, 
are doing something to popularise and simplify metal-work, 
one of the oldest of the crafts. 

After such efforts as these, the charge, which has in it many 
elements of truth, that manual training in our schools is 
wooden in conception, wooden in material, and wooden in 
execution, will no longer be levelled. One must admit that 
this book has not been written too soon. The old idea, that 
boys must work through paper, then cardboard, then wood, 
and finally — if they are at school long enough and are lucky — 
through a course of metal, is exploded. Hammered metal- 
work, simple wire-work, soldering, riveting, filing, drilling, are 
quite as useful in the education of young boys as cardboard 
modelling and wood-work. 

The acknowledgment by leading authorities on education 
that the child's only real and permanent paths to self -develop- 
ment lie along varied lines of interests is valuable even if it is 
belated, and the sooner this truth is recognized in our manual 

xi 



xii FOREWORD 

training-rooms, the better will our young people be prepared 
to fulfil their duties in later life as citizens. 

The toy interest is making itself felt, and to meet this phase 
of activity all kinds of earth material are being pressed into 
service. Scientific toys, so popular in this age of construction — 
electric, telegraphic, and telephonic apparatus, pumps, engines, 
motors, cranes — ^need a large element of metal, and the matter 
so clearly and simply set down in the following pages will bring 
to the young worker and to the teacher the results of a long 
teaching experience and of a wide and deep study of boy-life. 




Page 22, table, for ' silica ' read ' silicon. ' 

40, Fig. 9, for ' Crucible Steel Furnace ' read ' Cementation Furnace. 

47, last line, for 'matt ' read 'matte.' 

48, line 13, for ' matt' read 'matte.' 

50, lines 2 and 4, for ' copper oxide ' read * oxides of copper.' 
50, line 21, for ' copper oxide ' read ' cuprous oxide.' 

54, line 18, for ^Liquation' read 'Refining.' 

55, line 31, for ' ZnCog ' read 'ZnCOg.' 
71, column 2, penultimate line, for 'silica' read ' silicon.' 



METAL-WORK 

PART I 

THE METALLURGY OF THE METALS USED IN 
THE HANDICRAFT-ROOM 

CHAPTER I 
PROPERTIES OF METALS 

Introductory. — ^Metallurgy is one of the most ancient of 
the arts, and also one of the most interesting and instructive. 
The Age of Bronze is lost in remote antiquity, and no definite 
chronological line separates it from the preceding Neolithic or 
the New Stone Age. 

In prehistoric times we have evidences that bronze and 
iron were well laiown. Later, but in no known order, others 
were discovered, and we read in the Old Testament of gold, 
silver, copper, tin, iron, and lead. Many years later the 
Greeks discovered mercury, which, with the metals mentioned 
above, formed the complete list up to the end of the thirteenth 
century. Zinc, antimony, and bismuth, followed about a 
century later, and such metals as nickel and manganese were 
not discovered until the eighteenth century, and aluminium in 
the year 1828. 

Of the fifty-five elements classed as metals by chemists, only 
twenty-five occur in sufficient quantities, or possess the neces- 
sary properties, to be of any practical value, and of these 
twenty-five only about twelve are common. 

Weight. — All the common or better-known metals are 
bieavy, the degree of heaviness being measured by what is 
known as " specific gravity " — that is, by comparison with 

1 



METAL-WORK 



an equal bulk of water. The specific gravity of all metals is 
increased by mechanical treatment, such as hammermg, 
rolling, or wire -drawing. 

Table of Specific Gravity. 

(Weight of the metal compared with the weight of an equal bulk of 
water at 4° C. Water =1.) 



Aluminium . . 


. . 2-67 


Nickel 


. . 8-56 


Antimonj'^ 


.. 6-715 


Bismuth 


.. 9-82 


Zinc . . 


. . 7-20 


Silver 


. . 10-50 


Tin . . 


. . 7-29 


Lead 


.. 11-40 


Iron . . 


. . 7-22 


Mercury 


. . 13-29 


Copper 

/O _-i2- 


. . 8-92 

_• j_ . - /yc\. CkCi ■ 


Gold 
_.i- J i_ • _ J- i • 


. . 19-30 
J _ \ 



(Specific gravity X 62-28= weight per cubic foot in pounds 

Malleability. — Metals which have the property of being 
permanently extended in all directions by hammering or roll- 
ing, without severance of the constituent molecules, are said 
to be " malleable."' The degree of malleability is measured by 
the thinness of the sheet possible from the material. Most 
metals become more malleable with rise of temperature, but 
not all. As an instance, copper is very brittle near its melting- 
point, and zinc is only malleable through a small rise in 
temperature. 

The effect of hardness upon this property is very pronounced, 
and it is owing to this cause that copper is so much more 
malleable than iron at a low temperature. 

The presence of impurities also seriously affects the mal- 
leability of a metal, a trace of certain impurities in cases being 
enough to thoroughly destroy it. Very small percentages of 
bismuth in gold, or antimony in lead, render them quite brittle. 
There is every gradation between extreme malleability and 
brittleness. The first evidence of lack of malleability in a 
metal is shown by edge cracks, whilst if the quality is very 
deficient the metal crumbles under the hammer. 

Order of Malleability. 



1. Gold. 


4. Aluminium. 


7. Lead 


2. Silver. 


5. Tin. 


8. Zinc. 


3. Copper. 


6. Platinum. 


9. Iron. 



PROPERTIES OF METALS 3 

Ductility. — This is the property which permits a metal being 
extended in the direction of its length, as in wire-drawing. 
It is closely related to, though not identical with, malleability, 
as cohesion plays a more important part in this instance. 
Another important point is that ductility is greater in most 
metals when cold, and consequently nearly all metals for 
wire or tube making are drawn cold. 

The method of wire-drawing is simple. A rod of metal is 
taken (one end having been pointed), and is pulled or drawn 
through a tapered hole in a steel plate, the smallest diameter 
of the hole being somewhat less than the diameter of the rod 
itself. By repeating this operation through holes varying in 
diameter, wire of the required gauge is obtained. In wire- 
dramng the metal quickly becomes hard and brittle by com- 
pression, and requires frequent annealing. The property of 
ductility depends largely upon tenacity, and metals which are 
fairly soft and moderately tenacious are as a rule the most 
ductile. The tenacity, however, must be great enough to 
resist the force necessary to draw the metal. 

Lead is the lowest in order of ductility of the common 
metals, owing to its lack of tenacity. Steel wire is drawn down 
to a diameter of 0*008 inch, and platinum can be drawn to 
one-tenth of this diameter. 

The following table gives the order of ductility for the most 
common metals : 

Order of Ductility. 



1. 


Gold. 


4. 


Aluminium. 


7. Zinc. 


2. 


Silver. 


5. 


Iron. 


8. Tin. 


3. 


Platinum. 


6. 


Copper. 


9. Lead 



Tenacity or Cohesion. — This is the power to resist fracture 
by a stretching force, and is possessed by all the metals (except 
mercury) to a greater or lesser degree. It is dependent upon 
the cohesion of the particles. 

Tenacity is regarded as one of the most important of the 
properties of metals, for upon it depends their value for struc- 
tural purposes. This property is, like malleability, greatly 



METAL-WORK 



affected by the purity of the metal. In certain instances, 
however, the tenacity can be increased by the addition of 
what may be termed an " impurity/' Take, for instance, the 
addition of a small percentage of carbon in iron which converts 
it into steel, whilst, on the other hand, a very small trace of 
sulphur considerably reduces its tensile strength. Tenacity 
diminishes as the temperature rises, whilst anything which 
tends to harden a metal, such as hammering, rolling, or wire- 
drawing, will increase the tenacity. 

The following table gives the relative tenacity of the com- 
moner metals : 

Table of Relative Tenacities or Tensile Strengths. 
(Weight required to tear asunder 1 square inch.) 





Lhs. 




Lbs. 


Steel, cast . . 


. . 88,650 


Silver 


. . 24,000 


,, mild . . 


. . 73,500 


Aluminium . . 


. . 20,000 


Wrought-iron 


. 53,900 


Gold 


. . 10,000 


Brass 


. 42,000 


Zinc . . 


. . 3,500 


Wrought -copper . . 


. 34,000 


Tin 


. . 2,200 


Cast-copper 


. 24,250 


Lead 


. . 1,800 


Cast-iron 


. 19,480 







Hardness. — ^This is the property of resisting abrasion by 
scratching, cutting, or rubbing. The relative hardness of two 
metals can be judged by rubbing them together, the one 
which marks the other being the harder. This quality is 
easily determined by the action of a scriber or centre-punch 
during working, and students would do well to observe and 
note the results on the various metals used. The table given 
can be considerably enlarged in this way, and the effect of 
hammering, annealing and other processes obtained. 

The comparative figures given are according to Moh's scale : 



Lead . . 

Copper, gold, silver, alu 

minium, zinc, tin 
Nickel, iron . . 
Hard steel . . 



Table of Hardness. 

Can be marked by finger-nail 

> Easily marked with a knife 

Scratched by glass 
Scratches glass . . 



2 

2 to 3 

6 

over-6 



Fusibility. — All metals are solid at ordinary atmospheric 
temperature except mercury, but all can be reduced to fluidity 



PROPERTIES OF METALS 



by heating . Most metals and alloys expand during this J)rocess, 
and contract on cooling, the exception being type-metal (see 
p. 64). 

The following table of melting-points must be taken as ap- 
proximate in the higher temperatures, which are difficult to 
measure accurately. 

Table of Melting-Points. 

Tin 
Lead 
Cadmium 
Zinc 

Antimony- 
Aluminium 
Silver 
Gold 

Copper . . 
Cast-iron 
Nickel 

Wrought-iron 
Platinum 

Conductivity. — Speaking generally, all metals are good con- 
ductors of heat and electricity. It is interesting, however, to 
note in the table that all except tin, lead, and silver, are better 
conductors of electricity than of heat, tin and lead being better 
conductors of heat than electricity, and silver an equal con- 
ductor of both. Another remarkable instance is aluminium, 
which, though a poor conductor of heat, is a splendid conductor 
of electricity. It must always be remembered that con- 
ductivity and purity of metal go together, and that poor or 
inferior quality of metal gives inferior conductivity. Electric 
conductivity is greatly reduced by a rise in temperature of the 
metal employed. 



Degrees 


Degrees 


Centigrade. 


Fahrenheit 


231-9 


449-4 


327-4 


621-1 


320-9 


609-6 


420 


788 


630 


1166 


658 


1217-7 


960-5 


1761 


1063 


1945-5 


1083 


1981-5 


1240 


2264 


1452 


2646 


1520 


2768 


1755 


3191 



Relative Conductive Powers. 






Electricity. 


Heat. 


Silver 


1000 


1000 


Copper . . 


941 


748 


Gold 


780 


548 


Aluminium 


630 


80 


Zinc 


266 


90 


Iron 


155 


101 


Tin 


114 


154 


Lead 


76 


79 



6 



METAL-WORK 



Chemical Properties. — Most metals have considerable aflfinity 
for oxygen and combine rapidly with it^, especially in a moist 
atmosphere, when they are said to rust or tarnish. 

Gold, silver, platinum, aluminium, and mercury, do not 
combine with oxygen at ordinary temperatures. All the 
better-known metals are soluble in acids. Copper, silver, 
lead, zinc and iron dissolve in nitric acid, which should there- 
fore be used with care for cleaning the first three of these 
metals. Gold and platinum are not attacked by any single 
common acid, but are dissolved by a mixture of nitric and 
hydrochloric acids, which is therefore called " aqua regia."" 
Hydrochloric acid dissolves all metals excepting copper, 
silver, lead, gold and platinum. 



Strengths (in Tons per Square Inch). 
Maximum Strengths of Average Specimens at Temperature of 60° Fahrenheit. 



Name. 


Tension. 


Compression. 


Shear. 


Cast-iron 


7-5 


42 


14 


Wrought-iron 




24 


18 


20 


Steel, mild . . 




35 


26 


24 


,, tool 




40 


50 




,, piano-wire 




150 


— 




Copper, cast . . 




10 


35 


12 


,, rolled 




15 


40 


— 


,, drawn 




25 


— 


— 


Brass, cast . . 




18 


25 


— 


,, wire . . 




22 


— 


• — 


Muntz metal 




20 


— 


• — 


Gunmetal 




12 


48 


• — 


Aluminium . . 




9 


— 


• — ■ 


Zinc, cast 




1-5 


15 


— 


„ rolled . . 




8 


— 


— 


Tin 




1 


6 


— 


Lead . . 




0-75 


3 





CHAPTER II 
THE OCCURRENCE OF METALS IN NATURE 

Much has been written in recent years upon the condition 
of metals in their natural state^ and much more knowledge 
is continually being obtained through the study of ores and 
metals by the aid of the microscope and the more accurate 
methods discovered of determining high temperatures. 

The more common metals are not found to any great extent 
in pure or metallic form ; silver, mercury, copper, and bismuth, 
however, are occasionally found in this state, and also all the 
gold and platinum of commerce. Metals found in this state 
are said to be in a " native condition,"" but they are more 
generally obtained in chemical combination with other ele- 
ments, which usually conceal their metallic character. When 
in this latter condition, they are termed "minerals."' The ores 
of commerce are those minerals which contain a sufhciently 
large percentage of metal to make their extraction profitable. 
The amount of mineral necessary to warrant a mineral being 
termed an " ore "" varies with its commercial value. As an 
example, a mineral containing 10 per cent, of iron would be 
of no commercial value; with 10 per cent, of copper it would 
be well worth working; whilst 0-0028 per cent, (or 1 ounce per 
ton) would be regarded as a very valuable ore of gold. The 
less valuable elements which complete the mineral are usually 
of a rocky or earthy nature, and are called " gangue "" or 
" veinstuff."" Metals can often be partly separated from the 
waste matter by washing or crushing, but all need heat and 
some kind of flux for final separation. 

7 



8 METAL-WORK 

Gravels. — ^AU mineral substances are fairly heavy, and when 
the rocks or earthy matter containing them are broken up 
by storms and rains, the fragments are washed aw^ay by the 
running streams until they reach deeper water, where tte 
heavier portions accumulate on the bottom as gravel. This 
accounts for the formation of the alluvial gold deposits of 
California, the discovery of which caused the rush of 1849,. 
and in more recent years the Klondike rush. The Australian 
gold rush of about 1850 was also due to the discover}^ of valu- 
able gold alluvia, and some of the tin deposits in Cornwall 
are of a similar formation. These deposits are often called 
" placers,'" and the metals found in them are frequently of 
a remarkably pure nature. 

Beds. — Ores are often found in deposits lying parallel to 
the strata of the rocks in which they occur. Such deposits are 
termed " beds,'" and the " clay-band "' and " black-band "' 
ironstones, together with the great pyrite deposits of Northern 
Spain, are of this formation. 

Lodes, or Veins. — These may be described as cracks or 
fissures in the crust of the earth, which have been filled up 
with mineral matter of a totally different nature from the 
rocks in which they occur. They do not follow the stratifica- 
tion of the surrounding rocks, but cut through ^them, either at 
a high angle or quite vertical, although instances are [known 
where they have been nearly horizontal. Veins are usually 
found in rocks of great age, which give evidence of consider- 
able volcanic disturbance in the past, and vary considerably 
in the richness of their ore. The portion of the vein or lode 
which reaches the surface of the earth is called the " out- 
crop.'' A very large percentage of the ores of commerce are 
found in veins. 

Pockets, or Bunches. — These mostly occur in limestone 
rocks, and may be described as large holes, cavities, or 
chambers, which may or may not be connected with some 
vein or bed, and which have become filled with mineral 
matter. Fig. 1 shows the various formations. 



OCCURRENCE OF METALS 



9 



Forms of Ore — Iron. — Iron in a " native "" form occurs in 
minute quantities only, the most important ores being the 
oxidized minerals. 

The common ores of iron are — 

1. Bed Hcematite (Greek= blood-like) (FcgOg). 

This is the most important ore of iron. In its mineral state 
it sometimes looks black in colour, but is always red under 
the surface, and gives a red marking when rubbed on any 




Fig. 1. — OccTJKEENCE OF Ores. 



hard surface. It is fairly hard, and sometimes occurs in round 
lumps with a radial structure, when it is termed " kidney '' 
ore. It often contains 70 per cent, of pure iron, and, being 
remarkably free from sulphur, phosphorus, and other im- 
purities, has a great value for steel-making. 

The only British sources of supply are the Whitehaven 
district of Cumberland and the Ulverston district of Lan- 
cashire. Large quantities are shipped to this country from 
Bilbao in Northern Spain, Portugal, and Algeria. It is also 



10 METAL-WORK 

shipped from Elba to this country, but this ore is of a darker 
variety, and known as " specula.r " iron ore. 

Red and brown hsematite are also Yeiy abundant in Ger- 
many, Belgium, and North America, and these countries are, 
as a consequence, great steel-producing areas. Soft varieties 
also occur, and are known as red ochre, puddlers' mine, etc. 

In Labrador, New Zealand, Naples, and the West Indies 
there is found an ore consisting of ferric oxide combined with 
small quantities of titanium oxide (Fe203,Ti203), and known 
as " titaniferous iron ore ^^ or "ilmenite."' 

2. Brown Hcematite (FeaOg + a^HgO). 

This ore differs from red hsematite in that it has a certain 
proportion of water in its composition. In appearance 
brown haematite often resembles the red variety, but has 
generally more of a brown than black appearance, and always 
gives a brown marking. It is found in Northamptonshire, 
Lincolnshire, and the Forest of Dean, but, as it contains con- 
siderable quantities of sulphur and phosphorus, it cannot be 
used for high-grade steel. Importations of this ^variety from 
Spain and Algeria are almost as pure as red haematite. 

3. Magnetite or Magnetic (Fe304). 

This ore is black or grey in colour, and is usually crystalline 
or granular in texture. It gives a black streak in marking, 
and is always magnetic in its nature. The best ore of this 
Idnd contains as much as 72 per cent, of pure iron, and is 
very free from sulphur and phosphorus. Very little is found in 
Great Britain, but it is very abundant in Norway, Sweden, the 
United States, and Canada. In Sweden it is generally smelted 
with wood fuel, thus producing the famous Swedish soft iron. 

4. Spathic (FeCOg) (Ferrous Carbonate or Ferrous Oxide 
combined with Carbon Dioxide). 

This ore contains about 48 per cent, of iron, is of an 
ashen grey colour, with a pearly lustre, and gives a white 
marking. The only source of supply in Great Britain of any 
importance is the Br en don Hills in Somerset, but this supply 
is very limited. Small deposits are to be found in Durham, 



OCCURRENCE OF METALS 11 

Cornwall, and the Isle of Man. Its scarcity, however, limits 
its importance from these som^ces. When this ore is fomid 
mixed with other " gangue " or earthy matter, it is, however, 
the most important and plentiful of our British ores. When 
mixed with clay, it constitutes our clay-band ironstone of 
vSouth Wales and the Midland coalfields, and is of a compact, 
stony character, varying in colour from grey to brown. When 
mixed with bituminous or coaly matter, it forms the black- 
band ironstone of Ayrshire, Lanarkshire, and Staffordshire, 
and is found in the vicinity of the coalfields in these districts. 
As its name implies, it is of a black or dark colour, and coaly 
in appearance. When mixed with a small percentage of 
silicate and carbonate of lime (limestone), it forms the Cleve- 
land ironstone of North-East Yorkshire, which is of a pale 
green colour and very free from carbonaceous matter. 

These three ores are known as argillaceous* ores, and yield 
a phosphoric pig-iron by reason of the presence in each of 
a small percentage of phosphorus. As they almost invariably 
occur in the vicinity of coal-mines or limestone quarries (both 
coal and ironstone being required in the iron production), 
the ore has been worked, and to a large extent proved the 
foundation of the British iron trade. 

Iron Pyrites (FeSa). 

This ore, which is of a brassy yellow colour, should not be 
regarded as an ore of iron. It is very widely distributed, but, 
unfortunately, contains a large percentage of sulphur. For 
this reason it is regarded as an ore of sulphur rather than of 
iron, and is mined for the production of vitriol (sulphuric acid). 

Copper. — Sixty years ago Great Britain was the largest 
producer of copper in the world except Chili, but to-day 
comparatively little is raised. More than half the copper now 
produced comes from the United States of America, with 
Spain, Mexico, Germany, Chili, and Japan, accounting for 
another 30 per cent. The only important deposit of this 
mineral in its " native condition " is found near Lake Superior 
* Greek= white: of the nature of clay. 



12 METAL-WORK 

in Canada, where it occurs in large masses of pure copper 
associated with about 0-56 per cent, of silver. 

The principal ore of copper, from a commercial point of 
view, is copper pyrites, or sulphide of copper and iron 
(CugS'FegSg). An average analysis of good specimens of this 
ore gives 34-6 per cent, of copper, 30-5 per cent, of iron, and 
34-9 per cent, of sulphur. The British supply comes chiefly 
from Cornwall and Devonshire, but most of the ore smelted 
in this country is imported from Chili and Spain. Copper 
pyrites is of a bright golden yellow, metallic appearance, and 
gives a black marking on being scratched. The most impor- 
tant copper-smelting districts in the British Isles are Swansea 
and the north-east counties of England. North America and 
Germany export a large amount of copper in various forms 
into Britain. 

Lead. — The principal ore of lead is the sulphide " galena "" 
(PbS), which is found in brittle cubic crystals. It is grey in 
colour, and has a fine metallic lustre. Its formation causes 
it to break into fairly regular fragments. It is usually asso- 
ciated with quartz, and occurs in veins. The principal 
British mines are in Cornwall, Cumberland, Derbyshire, 
Northumberland, North Wales, the Isle of Man, and the Lead 
Hills of Lanarkshire; but the ore is widely distributed over 
the world. Galena always contains silver, but the proportion 
varies considerably, and an ore containing 120 ounces to the 
ton (0-36 per cent.) is considered to be extremely rich. Of 
late years the silver is always extracted, but some specimens 
of old lead command good prices in the market on account of 
the silver being still in the metal. On account of its softness 
and the slight effect of water or air upon it, lead is a valuable 
material for the lining of tanks, etc. A small quantity 
(0"3 per cent.) of arsenic has a hardening effect upon it. 

Zinc. — Zinc does not occur in native form. Its chief source 
is " blende'' or " black-jack " (ZnS). It varies in colour from 
white, through shades of yellow and brown, to black, the 



OCCURRENCE OF METALS 13 

darker colours being due to the presence of iron and cadmium. 
The more common mineral or ore is in association with 
galena. Large deposits of blende are to be found in Belgium, 
Germany, Russia, Australia, and many parts of the United 
States. It is also found in North Wales, Cornwall, Cumber- 
land, Derbyshire, and the Isle of Man. Although not so soft 
as lead, its uses are very similar, and it is also used to coat or 
galvanize iron to prevent it rusting. It has many valuable 
uses in medicine. 

Tin. — The only ore of tin is '"tinstone," or " cassiterite " 
(SnOg), which is black or deep brown in colour. It is often found 
in the form of crystals which have a brilliant lustre, and in 
well-defined veins. It is heavy and extremely hard — so hard, 
indeed, that a knife will not scratch it. Owing to these 
qualities, it is often found in gravel form through being 
washed down from the rocks by running streams. In such 
cases the ore takes the form of rounded masses, is very pure, 
and is termed " stream-tin. "" 

Prospectors endeavour to detect streams containing stream - 
tin, and then follow the stream towards its source up to the 
point where the ore ceases to be found. They then make a 
thorough examination of the surrounding rocks, which 
generally leads to the discovery of the vein. The only 
European source of tinstone (other than Spain) is the Cornish 
deposits, which are known to have been worked since before 
the time of the Romans ; but the Cornish gravels are now 
worked out, and the present supply is obtained from the 
veins. Other deposits are known in Argentina, but over 
60 per cent, of the world's supply is found in the British 
Empire. Australia and the Far East (Mullaca Blanca and 
Borneo) are rich tin-bearing districts. 

Aluminium. — Although aluminium is not found in compact 
mineral masses, it is one of the most plentiful elements in nature. 
It occurs in greatest proportion combined with oxygen as 
■" alumina "" (AI2O3), one of the compounds which enters most 



14 METAL-WORK 

largely into the composition of the superficial strata of the 
earth. It forms the basis of all clays^ and is present in varying 
percentages in almost all soils. The principal ores from which 
the metal is obtained are bauxite (Al203,2H20) and cryolite 
(AlFg'SNaF), both of which, while being freely and widely 
distributed, are found in a very pure state in many parts 
of France, Ireland, and North America. Bauxite takes 
its name from Baux — a French district where it was first 
found. Alumina occurs nearly pure in corundum. The 
sapphire and ruby are composed of alumina combined with 
a small percentage of oxide of chromium, Emery is another 
form of alumina, coloured with oxide of iron and manganese. 



CHAPTER III 
MANUFACTURE OF CAST-IRON 

In Chapter 11. it was pointed out that iron does not occur 
to 3i>nj great extent in a metallic state in nature. Where 
native metal does occur, it is in all probabiHty meteoric iron. 

Manufactured iron is marketed in four different forms, as 

follows : 

1. Pig or cast iron. 

2. Wr ought-iron. 

3. Mild-steel. 

4. Cast-steel. 

When it is considered that each of the succeeding forms is 
derived initially from pig-iron, it will be readily admitted 
that the production of pig-iron is the largest and most 
important process in the whole science of metallurgy. 

Iron-smelting is also one of the oldest arts known to man, 
and it is mentioned in the Old Testament (Gen. iv. 22) that 
one Tubal-cain was a whetter or sharpener of brass and iron, 
and Tubal-cain is said to have been of the sixth generation 
from Adam. The period when the process of iron-smelting 
was introduced is very uncertain, but Max Miiller, in his 
" Science of Language,'' states that " the original language- 
speakers, whose language perished long before the historic 
age began, were acquainted with the most useful metals, and 
were armed with iron hatchets.'' The early methods of 
reduction were very simple, as no blast was used, the ore 
being simply reduced with wood or charcoal as fuel. Probably 
the first great improvement was the introduction of blast, and 

15 



16 METAL- WORK 

in ancient sculptures of about the year 1500 B.C. iron pro- 
duction or working, with artificial blast supplied by bellows, 
is depicted. Historians of times before the Christian era 
continually refer to the metal in some form or other. 

Bellows with valves were invented by the Romans in the 
fourth century, and were used generally until the year 1620, 
when the blowing -engine was introduced. The first step 
towards the present type of blast-furnace was probably an 
upright furnace of larger dimensions than hitherto used, 
which made its appearance in the fourteenth century. 

We have evidences and records of the " blast " furnace 
being used in Sussex about this period. Iron-smelting was 
carried on in that district, in South Wales, and in the Forest 
of Dean to a large extent. Indeed, so great was the industry 
in Sussex that an Act of Parliament was passed in 1584 for- 
bidding the erection of any more furnaces, because the drain 
upon the forests of the district for timber to use as fuel was 
seriously afl^ecting hunting and shipbuilding. After this 
period many attempts and experiments were made with 
mineral fuel, but none were successful until 1735, when the 
use of coke was introduced by Abraham Darby. This change 
tended to move the ironworks from the forest areas to the 
coalfields. 

In 1828 the " hot "" blast instead of " cold "' was introduced, 
a process which saves from 15 to 40 per cent, of the fuel, and 
also increases the productive power of the furnace. The blast 
is heated in regenerative stoves which burn the waste gases 
from the furnaces, and passes into use at a temperature of 
about 750° and a pressure of 5 pounds per square inch. One 
of the most important features of the blast-furnace is that 
the production is continuous, and the furnace used without 
cessation for a number of years, until burnt out. 

In manufacturing pig-iron from the ores a preliminary prep- 
aration is necessary before smelting. The object is threefold: 

1. To remove extraneous matters, such as clay, sand, and 
rock. This is done by means of a rapid stream of water. 



MANUFACTURE OF CAST-IRON 17 

2. To get the ore to a suitable size. This is done by break- 
ing either by hand or by a mechanical ore-breaker, which 
reduces the larger pieces to a size varying from the size of 
ordinary road-metal to 4-inch cubes. 

3. To remove water, organic matter, sulphur, and other 
volatile matters. This is done by means of calcination or 
roasting. 

This last process is the most important, and can be per- 
formed by roasting in piles or heaps in the open air, sometimes 
with the addition of walls to retain the heat, or in kilns or 
furnaces of special construction, so that air and temperature 
are more under control and a saving in fuel effected. 

The open-air method consists in spreading a layer of coal 
about 12 inches deep upon a specially levelled piece of land. 
Upon this a 12-inch layer of ore is placed, and alternate layers 
of coal and ore are placed in the proportions of 3 hundred- 
weights of coal to 20 hundredweights of ore. The usual size 
of the heaps is from 14 to 15 feet wide, 8 to 10 feet high, and 
of varying length up to about 100 feet. The fire is lighted at 
the bottom and allowed to burn gradually, any local tendency 
to fire too quickly being checked by applying small ore or 
ashes. 

In the second method the walls are often formed of the 
larger pieces of ore. 

The kiln or furnace method is generally preferred. Kilns 
and furnaces are circular or rectangular structures of masonry, 
or boiler-plates lined with fire-bricks, with openings at the 
bottom to admit air and to allow the removal of the calcined 
ore, and are charged, or loaded, from above. This form is 
very common in South Wales. The latest and perhaps most 
perfect form is the Gjers Calcinator. It consists of plates 
lined with fire-bricks, and in shape is a cylinder upon an 
inverted frustrum of a cone. The bottom rests upon a cast- 
iron ring, which is supported by short pillars, and through 
the centre of the bottom projects a cone about 8 feet high 
and 8 feet base, which directs the calcined ore outwards 

2 



1 



METAL-WORK 



through the pillars. The widest diameter is about 20 feet, 
and the height about 25 feet. Air is admitted through holes 
in the brickwork near the base, as shown in Fig. 2. The ore 
remains in the kiln from two to three days, and about 1 hun- 
dredweight of small coal is burnt to each ton of ore. The 
effect of calcination upon the ore is to make it porous, thus 
helping the subsequent smelting, and the loss in weight is 
about 30 per pent., varying with the amount of carbonaceous 

^ Rails for Carrying Ores 

t ■?• f 



Steel Casing 
Brick Lined 




Supporting 
Pillars. — ^1 



Fig. 2. — Calcinator. 

matter in the ore. Moisture and carbon dioxide are also 
removed by this treatment. Black-band ironstones often 
contain enough carbonaceous matter to effect calcination 
without the application of any fuel other than that necessary 
to start com±bustion. 

The blast-furnace which is now generally used in smelting 
the ores for the production of pig-iron is represented in section 
in Fig. 3. The outside shell is of boiler-plates, and the 
interior of two linings, the one immediately next the plating 



MANUFACTURE OF CAST-IRON 



19 



being of ordinary bricks, and the inner one of refractory fire- 
bricks. 

The general arrangement of the furnace is as shown in 
Fig. 3. The shaft (which is about 80 feet high, with a 
diameter of 20 feet at its widest part, called the " belly ""), is 
shaped like two truncated cones, which surmount a cylindrical 
portion, having a diameter of about 10 feet. The lowest 



Hopper 



Charging 
Platform - 



Counter -Weight 



- Candle 



Waste Gases 
to Stove 




Fig. 3. — Blast-Furnace. 



part, in which the fused products collect, is called the " hearth.'" 
In this portion several openings will be observed. The open- 
ing marked " tapping-hole " is that through which the molten 
iron is run, and a little above is the slag-hole, through which 
the lighter slag is withdrawn. A little higher still come the 
openings through which the tuyeres introduce the blast. The 
lower portion, which is subject to the fiercest heat, is cooled 



20 METAL-WORK 

by the constant circulation of water through pipes encircling 
the hearth. The main portion of the furnace structure is 
carried upon columns. The throat is about 16 feet in 
diameter, and is kept closed except when materials are to be 
added. Then the coiuiter-balanced cone or bell forming 
the stopper is lowered, allowing the collected ore and fuel 
in the V-shaped space to enter the furnace. The waste 
gases pass through the down-cast shaft into the stoves, and 
are used to heat the blast. 

These stoves contain a large number of small brickwork 
flues. The bricks retain the heat, and when thoroughly 
heated the gas is diverted into another stove, and the blast 
allowed to pass through the heated one before entering 
the furnace. On becoming cooled the stoves are changed 
and the cool one reheated. The gas and the blast pass 
through the stoves in opposite directions. It will be noted 
that this arrangement necessitates at least two stoves for 
each furnace. The charge, or material, usually consists of 
5 hundredweights of ore, 2 hundredweights of limestone for 
flux, and 5 hundredweights of coke for fuel, and is repeated 
as often as the capacity of the furnace will allow, usually about 
every fifteen minutes. The materials, ore, fuel, and flux, are 
mixed before being supplied to the furnace. The shape of the 
stopper well distributes the mixture, and when the furnace is in 
full blast the metallic portion of the charge fuses and falls into 
the hearth. The general shape of the interior materially helps 
this operation. When sufficient molten metal has accumulated, 
the clay stopper of the tap-hole is pierced with a pointed bar. 
This allows the metal to flow along a prepared channel in sand 
to the moulded bed. When it has solidified and cooled, the 
metal is broken into lengths of about 2 feet. The usual period 
between the " blows "" or " draw-offs " of an average furnace is 
about twenty to thirty hours, the slag being run off con- 
tinuously. 

The tendency of late years has been in favour of larger 
furnaces, many reaching a height of nearly 100 feet; but whilst 



MANUFACTURE OF CAST-IRON 21 

it cannot be disputed that the productive power is increased, 
it has also been proved that the increase is not in proportion 
to the increased cubical capacity. At the present time the 
inclination is to reduce the size once more. 

The chemical changes in the blast-furnace are fairly simple, 
but in considering these changes the conditions under which 
the furnace works must be borne in mind. 

The first change, which takes place in the upper portion, is 
the reduction of the ore to a porous mass by the carbon 
monoxide, which rises from the lower layers of burning fuel. 
The temperature at this point is not nearly sufficient to melt 
the iron ; hence it sinks down until it reaches a point wheie the 
heat is sufficiently great to decompose the limestone and to 
commence the carburization of the metal, the carbon being 
derived from the fuel. 

The final action is the combination of the lime and gangue 
to form slag, and the fusion of the spongy iron now rendered 
more fusible by its dissolved carbon. The iron in passing 
through the hottest part of the furnace converts some of the 
silica into silicon. This substance, together with a small part 
of the sulphur, any manganese present, and the carbon, all 
combine with the iron. As stated previously, the slag, being 
lighter, floats on the top and is drawn o& through the slag-notch. 

Pig-iron is placed on the market in three grades or classes : 

1. Grey Pig-iron, which has a crystalline or granular appear- 
ance and a dark grey colour, is soft and deficient in 
strength. It is very fluid when melted, is used for ordinary 
castings, and contains from 0-6 to 1-5 per cent, of carbon 
chemically combined, and from 2*9 to 3-7 per cent, of free 
carbon as graphite disseminated through the mass of the metal. 

2. White Pig-iron presents a white, close appearance, is 
extremely hard, and flows sluggishly. On this account it is 
used for very large castings, and a considerable amount of it 
is converted into wrought-iron. It contains from 3 to 5 per 
cent, of carbon all chemically combined. 



22 



METAL-WORK 



3. Mottled Pig-iron presents the appearance of white iron 
with grey spots, and is of variable hardness; it is sometimes 
produced by mixing " white "" and " grey "" pig-iron. 

The average composition of pig-iron is — 



Carbon 


2-30 to 5-50 per cent 


Silicon 


0-13 „ 5-70 


Manganese . . 


0-00 „ 7-60 


Sulphur 


0-00 „ 0-87 


Phosphorus 


0-00 „ 1-66 


Iron 


97-57 „ 88-66 



The appended diagram shows the chief reactions and the 
involved products formed in the production of pig-iron : 



Charge. 



Output. 



Iron Ore ^ 



Lime Stone 



Coke 



Air 



__ ,S^ Pig Iron 




Waste Gases 



Nitrogen 



Note : — Dotted Lines Indicate very small Quantities. 



CHAPTER IV 
MANUFACTURE OF WROUGHT-IRON 

Wrought-iron can be obtained by two methods: 

1. By direct reduction of the ore, thereby dispensing with 
the blast-furnace processes. 

2. From cast-iron. 

By the first method, which is the older, very pure iron ores, 
such as magnetic oxide or hsematite, are required. Cold blast, 
with charcoal as fuel, is used, and the temperature is kept low 
enough to prevent the carbon combining with the iron. The 
method is not very common now, although it is adopted in 
some quarters of Europe, particularly in the Pryenees and 
districts of Spain. In parts of the United States, where 
charcoal is plentiful, a modern application of the process is 
still carried out with hot instead of cold blast. 

The fault of this direct method lies in the fact that part of 
the carbon of the charcoal fuel combines with the m.etal, and 
forms a steely iron. It is also slow and very expensive in 
fuel. The charge varies from 3 to 10 hundredweights, accord- 
ing to the size of the hearth, and only produces 1 ton of iron 
to 3 tons of fuel. 

The second method is much more common. As has been 
previously stated, pig-iron is far from pure, containing 
variable quantities of carbon, silicon, sulphur, phosphorus, 
and manganese. In order to obtain wrought-iron, which is 
almost chemically pure, these impurities must be removed, 
and this is done by puddling, or by refining and puddling. 

If the pig-iron used is " white,"" the puddling process can 
be carried out directly; but if " grey "" pig-iron is used, a 

23 



24 



METAL-WORK 



preliminary refining is required, which practically converts 
it into " white "" by the removal of its impurities, chiefly 
silicon. This "refining"' is done in a " finery "" or furnace, 
as shown in Fig. 4. The hearth is about 4 feet square and 
18 inches deep, with a bottom of refractory sandstone and 
sides of water-cooled cast-iron blocks, as shown in Fig. 4. 
The blast is supplied by six or eight tuyeres inclined at an 



Supporting 
- Columns 

Water Supply- 




Valve 



Fia. 4. — 'Refinery or " Finery. 



angle of 30 degrees. The fuel used is coke. The blast impinges 
on the molten metal, and so forms an oxidizing atmosphere, 
which, whilst carrying off a portion of the carbon, reduces the 
silicon by as much as 4 per cent. When the requisite degree 
of purity is reached, the iron is run off into moulds and cooled 
by water. The operation lasts from two to three hours, and 
is very wasteful in fuel and metal, the latter losing 10 to 12 
per cent, of its weight. 



MANUFACTURE OF WROUGHT-IRON 



25 



The " puddling "" process was introduced in 1784 by Henry 
Cort, and is now almost universally used. Up to the date 
of this invention the sulphur in coal and coke had prevented 
their use in the manufacture of wr ought-iron, but in the 
Cort process a small reverberatory furnace is employed (Fig. 5), 
in which the fuel is burnt out of contact with the iron, and a 
strong draught, induced by a chimney 40 to 50 feet high, 
controlled by a damper. The hearth or bed of the furnace 
is carried by a cast-iron plate having a free air circulation 
underneath, and is usually about 6 feet long, with a bridge 
or dwarf wall built at each end. The hearth plates are pro- 
tected from the heat by a coating of fettling from 2 to 3 inches 




Door for 

Extracting 

Blooms 



Fig. 5. — Puddling Furnace. 

thick, which is renewed as it wears away. This fettling con- 
sists of haematite, hammer scales, cinder, or some such sub- 
stance rich in oxygen, and is often termed " puddlers' mine.'" 
The procedure adopted in the process is as follows: The 
fire is started and the furnace heated up. The charge of pig- 
iron is then introduced, and the temperature increased to a 
sufficient degree to reduce the metal to a molten state, which 
usually takes thirty to forty minutes. When perfectly liquid, 
the damper, which is under control of the puddler, is partly 
closed to reduce the draught and temperature, and the fire- 
door opened. The incoming air immediately oxidizes part 
of the carbon, and slag begins to form. 



26 METAL-WORK 

At this stage the metal shows little or no movement, but 
in a short time numerous blue flames, called " puddlers' 
candles/' appear, due to the oxides in the fettling reacting 
with the carbon of the iron to form carbon monoxide. The 
escape of gas soon becomes so rapid that the metal appears 
to boil, and is briskly stirred by the puddler. As the forma 
tion of carbon monoxide slackens owing to the diminishing 
carbon in the iron, the liquid becomes pasty. As much of the 
slag as possible is removed, and the puddler works the iron 
into balls, or blooms, of from 60 to 80 pounds weight, 
which are removed from the furnace and hammered, to force 
out any slag and to weld the iron into a solid mass. It is 
then rolled. 

The iron is now known as "puddled bar,'" and is not suffl- 
ciently homogeneous to be marketable. 

" Merchant bar " is formed by cutting puddled bar into 
lengths, and fastening it into bundles or faggots by scrap or 
iron wire. It is heated to welding heat and rerolled. This 
faggoting, reheating, and rolling, may be carried out four times 
in all, and each time the material is improved by the gradual 
elimination of entangled slag, and by the more pronounced 
fibrous structure due to the rolling. Experience has proved 
that after this number of operations the material deteriorates, 
owing to the formation of " burnt "" iron. This burnt con- 
dition is probably due to the oxidation taking place during 
the repeated journeys from the furnace to the mill. Iron in 
this state loses its malleability. 

The market qualities of wrought-iron are — 

Common iron (merchant bar) = puddled bar once reheated. 
Best iron = „ „ twice „ 

Best best iron = „ „ thrice „ 

Treble best iron = ,» „ four times reheated. 

Wrought-iron is subject to two great faults — " cold short- 
ness,'' or the tendency to fracture when bent cold, due to 
the presence of small quantities of phosphorus; and "red 
shortness,'' or the tendency to be brittle when heated, due 



MANUFACTURE OF WROUGHT-IRON 



27 



to the presence of sulphur, which hinders or prevents the 
metal being forged or welded. " Cold short '' iron will work 
satisfactorily when hot, and " red short " when cold. Ac- 
cording to Professor Thurston, cold rolling improves iron in 
tenacity and elasticity, and increases the uniformity of 
structure, but these improvements are obtained at the expense 
of ductility. 

Numerous attempts have been made to replace the heavy 
manual labour required in puddling by machinery, but with 
little success. Recently, however, fairly favourable results 
have been obtained by the Banks revolving furnace. This 
consists of a revolving cylindrical drum into which the fire 
is forced by a blast-fan. Many firms who adopted the method 
have since abandoned it, probably owing to the wear and 
tear. The production of wrought-iron has greatly decreased 
in modern times, having been replaced by mild-steel, which 
can be produced cheaper, and is equally good, if not superior, 
for constructional purposes. Its chief remaining uses are 
probably for chain-making (on account of its welding prop- 
erties), and as the base metal in the production of cast-steel. 



Composition of Wrought Iron. 



Carbon 
Silicon 
Phosphorus 



0-10 to 

traces ,, 

0-04 „ 



C-30 
0-10 
0-20 



Sulphur 
Manganese 
Iron . . 



0-02 to 0-15 
traces ,, 0*25 
99-10 „ 99-80 



CHAPTER V 
MANUFACTUEE OF MILD-STEEL 

The name " steel " was formerly used to define those 
varieties of iron which could be hardened by heating to red- 
ness and cooling by sudden immersion in water. 

In 1855 Sir Henry Bessemer discovered and patented a 
process for " the manufacture of malleable iron and steel 
without fuel/' and in 1862 another method was introduced 
called " the Siemens-Martin/' in which gas was used as fuel. 
These two processes necessitated a new definition of steel, as 
they both yielded a product containing under 0*5 per cent, of 
carbon, and which still had the malleable properties of iron. 
Since the hardening properties of steel depend upon the 
amount of carbon present, a classification based upon the 
percentage of this element has been adopted. When the 
amount of carbon is less than 0'5 per cent., the material is 
termed " mild-steel,"" and does not necessarily harden when 
heated and quenched. When over 0*5 per cent, and under 
1-5 per cent, of carbon is present, it is known as " cast-steel,"" 
with specialized names, such as tool, crucible, or hard steel. 
Mild-steel is always produced by adding the required per- 
centage of carbon to pig-iron from which the carbon originally 
present has been removed. Whilst many different processes 
are in use at the present time under special names, all are 
modifications or adaptations of the two processes already 
named — the Bessemer and the Siemens -Martin. 

The Bessemer Process. — This process, which was patented 
by Sir Henry Bessemer on December 7, 1855, was the outcome 
of his endeavour to find a stronger and tougher material for 

28 



MANUFACTURE OF MILD-STEEL 



29 



making cannon. It consisted in burning out the carbon and 
silicon from molten pig-iron by a quicker method than that 
of the puddling furnace — namely, by passing a blast of cold 
air at a pressure of 25 to 28 pounds per square inch through 
the liquid metal, and afterwards adding carbon in the form 
of spiegeleisen (iron containing some manganese and much 
carbon) to recarbonize the charge, and so convert it into 
steel. 



Steel Casing 



Basic Lining 




Fig. 6. — Bessemer Converter. 



Whilst it appears somewhat strange that by blowing cold 
air through red-hot metal it can be raised to white-heat, it 
must be remembered that combustion takes place within the 
metal, the impurities of which act as the fuel. The con- 
verter itself, which is shown in section in Figs. 6 and 7, con- 
sists of a mild-steel or wrought-iron shell | to 1 inch thick, 
carried on a cast-iron ring. This cast ring forms the blast- 
box at the base, into which the tuyeres are fixed. The 
tuyeres usually consist of fireclay cylinders about 2 feet long. 



30 



METAL-WORK 



and from 8 to 10 inches diameter, perforated by ten or twelve 
I -inch diameter holes throughout their length. They pass 
from the blast-box to the inside of the converter through the 
lining, and project slightly, and are fastened with stops 
which allow them to be taken out and renewed when 
required. 

The whole arrangement is supported about the middle by 
another cast-iron ring provided with two trunnions, which 




Converter in Position 
for Pouring 



£\ lor rh 



Ladle in Position 
for Filling Ingots 



Counterweight 
Ingot - 



Fig. 7. — ^General Arrangement of Bessemer Plant. 

allow tilting to receive or discharge the metal. One of these 
trunnions is fitted with a turning gear, consisting of a toothed 
wheel, which gears with a rack attached to a hydraulic ram. 
The converter can rotate through 300 degrees . The other trun- 
nion is hollow, and is used for the passage of the blast from the 
blower to the blast-box. The converter is lined with about 
12 inches of fireclay or a coarse siliceous rock termed 
" ganister,"' which is crushed to powder and mixed with a 
little water before being applied to the interior of the vessel. 
It is then allowed to dry slowly. 



MANUFACTURE OF MILD-STEEL 31 

The Method of conducting the Blow. — The pig-iron is first 
melted in a cupola, or, in modern steelworks, carried direct 
from the blast-furnace in a ladle. A charge of from 5 to 12 
tons is usually run into the converter, which is tilted to receive 
it. Whilst the converter is in this position the molten metal 
does not reach the tuyere holes. The blast is now turned 
on and the converter rotated to an upright position, but the 
air-pressure of 25 pounds per square inch is sufficient to 
prevent the metal running through the tuyeres. At first a 
shower of sparks is ejected, and a short yellow flame appears 
at the mouth of the converter. During this period a vigorous 
combustion takes place, accompanied by a great rise in tem- 
perature, due chieflj' to the oxidation of the carbon and 
silicon. The former, being changed into carbonic oxide, rises 
in bubbles through the molten iron, throwing the whole charge 
into violent agitation, known as the " boil.'^ At this stage 
the flame at the mouth of the converter steadily increases, 
and is accompanied by dazzling showers of sparks at irregular 
intervals. 

The flame reaches its maximum about ten minutes after 
the commencement of the boil, and after about another twenty 
minutes it decreases, and at the same time changes to an 
almost transparent pale red tint. The showers of sparks 
likewise diminish. 

This indicates that the metal is thoroughly decarbonized. 
The converter is now turned into a horizontal position, the 
blast cut off, and the necessary amount of spiegeleisen, which 
has been melted in a cupola, is added, the amount to be used 
having been previously calculated, so as to produce the desired 
grade of steel. After standing for a few minutes, to allow the 
slag to separate and the carbon to mix thoroughly with the 
metal, the mouth of the converter is further lowered and the 
steel poured into a ladle, and from the ladle into ingot moulds, 
which are fixed in position below the tap-hole. These ingot 
moulds are of cast-iron, open top and bottom, slightly tapered 
inside to allow of free removal. In order to prevent the 



32 METAL-WORK 

formation of bubbles in the metal, it is poured into a feeding- 
mould, which is usually about 6 inches longer than the ingots, 
and is connected with the bottom of each by means of fireclay 
tubes. The ingots vary in height from 3 feet to 4 feet 6 inches. 
Immediately the ingot solidifies it is removed to gas-heated 
soaking-pits, in which the metal remains until required for 
rolling. 

It will be noted that the metal is never allowed to lose its 
heat in its course from the blast-furnace to the marketable 
finished article. The speed at which the Bessemer plant can 
be worked depends on many circumstances, but chiefly on 
the speed with which the ingots can be transferred to the 
soaking-pits and the moulds replaced. The usual British 
practice is to work two converters, each blowing once in forty 
minutes. The lining is examined after each blow, and re- 
paired if necessary; but a good lining is expected to give 
500 blows before entire renewing is necessary. The bottoms 
and tuyeres require replacing more frequently, seldom lasting 
more than twenty to thirty blows. 

The action of the blast on the metal in the converter con- 
sists first in oxidizing the silicon and manganese, producing a 
fusible slag. When the silicon is nearly oxidized the carbon 
is attacked, and the action proceeds until purity is reached, 
which is indicated by the flame. 

The silicon, manganese and carbon in a 10-ton charge of 
Bessemer pig-iron usually amounts to about 12 hundred- 
weights, and the calorific power of silicon is 7,830, and carbon 
2,400, in British thermal units. From these figures it will be 
understood how the great heat is obtained which is necessary 
to keep the metal in a state of fusion. When the carbon is 
reduced to about 0-2 per cent, the metal begins to oxidize, 
this causing the change in the flame. The oxidized metal is 
brittle and unworkable. To remove this fault, and at the same 
time to add the necessary carbon for converting it into steel, 
the spiegeleisen is added. The manganese in the spiegeleisen 
becomes oxidized and passes into the slag, whilst the carbon 



MANUFACTURE OF MILD-STEEL 33 

enters the iron. It is essential that sufficient manganese be 
added to remove the oxygen from the iron, and it is also 
suggested that the manganese serves to remove any residual 
silicon. 

Sulphur and phosphorus are not removed by this process, 
as they cannot be oxidized from pig-iron. Usually 0-048 per 
cent, phosphorus and 0-018 sulphur are found in good average 
pig-iron, and almost the same percentages in finished Bessemer 
steel. It is therefore highly important that iron as free as 
possible from these impurities should be employed. Grey 
pig, which is produced from red haematite or magnetite, and 
sometimes termed " Bessemer pig-iron,^' is used. 

Bessemer pig should contain at least 2*5 per cent, silicon, 
because upon the oxidation of this silicon depends the heat 
during the early part of the blow. The process described is 
known as the " acid " Bessemer process, because of the 
siliceous nature of the ganister lining. 

Basic Process. — As the demand for Bessemer steel grew, 
and as iron containing phosphorus was useless in the process, 
some means of extracting this impurity became necessary, as, 
unfortunately, the more plentiful supply of pig-iron contained 
too large a percentage of phosphorus for producing mild-steel. 

The solution of the problem came from Mr. S. G. Thomas. 
He, in conjunction with Mr. C. P. Gilchrist, a South Wales 
chemist, experimented, and in 1878 found that if the converter 
was lined with blocks or bricks made of " dolomite " (car- 
bonates of lime and magnesia), and the blow continued for a 
short time after the carbon had gone, the phosphorus also 
almost disappeared from the iron. It is only diiring this 
" after-blow " that the phosphorus is removed. 

There is very little difference in the mechanical movements 
or the chemical reactions in the " acid " and " basic "" pro- 
cesses, except that the silica and carbon are more completely 
removed. The phosphorus passes into the slag as calcium 
phosphate. The " basic " process is chiefly used where phos- 
phoric ores are plentiful, notably in Belgium and Germany. 

3 



34 



METAL-WORK 



Siemens or Open-Hearth Process.— In 1856 Friedrich 
Siemens invented the process which takes his name. By his 
process, which is analogous to the puddling process, the 
decarburization of the pig-iron is effected by pure oxidized 
iron ore, usually Spanish red haematite. The furnace, which 
is of the reverberatory type with regenerative chambers, was 
originally heated by solid fuel. In the year 1861 Sir W. 
Siemens invented his "gas-producer,'' which supplies the 
furnace with a special gaseous fuel. The regenerative cham- 




FiG. 8. — Siemens' Regenerative Furnace. 



bers are built of chequered brickwork, as shown in Fig. 8. 
The chambers are always built in pairs, and are alternately 
heated by the hot gases which descend through them to escape. 
When one pair is heated, the waste heat is turned into the 
other pair, and the air and gas, using separate passages, are 
passed through the hot ones before entering the furnace. 
The flow is reversed about every thirty to forty minutes. 
It is possible to produce and maintain a higher temperature 
by this process than by any other. 



MANUFACTURE OF MILD-STEEL 35 

The Process. — The charge depends upon the size of the 
furnace, for a 30-ton furnace (the usual size) consists of 
22 tons of pig-iron and 8 tons of haematite. The pig-iron is 
first charged, and in about five or six hours is melted down. 
When the metal is quite liquid, the gradual addition of the 
ore is commenced. At first small bubbles appear, and as more 
ore is added flames of carbon monoxide are observed. 
Gradually the metal comes to the " boil," and is seen in violent 
agitation, followed by a gradual subsidence. When it is 
completely tranquil, samples are taken. If the percentage of 
carbon is sufficiently low, the temperature of the furnace is 
raised to its maximum, and the metal runs into ladles and 
again into ingots, similar to the Bessemer process. 

As the metal is being run into the ladle, f err o -manganese 
or spiegeleisen is added, thus carburizing the metal to the 
required degree. The time occupied in this process is much 
longer than that required for an equal weight of metal by 
the Bessemer process, being about fourteen hours per charge, 
but it allows better control of the operation. The quantity 
of steel obtained is about equal to the charge of pig put in, 
varying slightly with the quality of the ore. 

Chemistry of the Process. — The oxygen in the hasmatite 
effects the oxidation of the carbon in the pig-iron, which 
largely passes off as carbon monoxide, as in the puddling 
process. The quantity of silicon in the pig-iron should be 
low, as any excess delays the process. Phosphorus and 
sulphur must be absent (or of small percentage), as in this 
process they are not removed. The percentage of manganese 
is of little importance, except that it tends to delay the 
working if present in any large amount. This process is also 
knowTi as the " pig and ore process,"" on account of the 
materials composing the charge. 

Siemens- Martin Process. — About the time Siemens invented 
his process, Messrs. Martin conceived the idea of using scrap 
iron or steel instead of ore. A similar process had been tried 
in 1844 by J. M. Heath. This, however, failed owing to his 



36 METAL-WORK 

inability to obtain a sufficiently high temperature. In this 
process, commonly called the " pig and scrap/^ the percentage 
of carbon to be reduced is diminished, as scrap-iron is used 
instead of ore. Scrap to the extent of eight to ten times the 
weight of pig-iron is frequently used, and the percentage of 
carbon present on fusion is about 1. 

Decarburization is effected by the oxides formed on the 
scrap. The loss in this process is about 8 per cent, of the 
total charge. Except in the points stated, the process is 
carried out as in the Siemens process, and in both cases the 
hearth is made up of highly siliceous materials, so little phos- 
phorus must be allowed in the charge. 

One advantage of this process is that it provides a use for 
the large quantities of scrap produced in manufacturing 
operations. 

Basic Open-Hearth Process. — In any open-hearth process, 
if a sand bottom is used, the pig-iron employed must be free 
from phosphorus. 

After the success of the Thomas -Gilchrist process of lining 
Bessemer converters with calcined dolomite, similar material 
was introduced for the hearth of the Siemens-Martin furnace. 
As phosphoric pig-iron can now be treated, this process is 
amongst the leading methods for steel production. Many 
attempts have been made to combine the certainty of the open- 
hearth process with the rapidity of the Bessemer. The most 
successful are the Bertrand-Thiel and the Talbot. In the former 
the pig-iron is first treated in a basic-lined furnace, termed 
the " primarj^"" for the removal of silicon and phosphorus. 
It is then decarburized and finished in a " secondary "" furnace. 
The time required is much shorter than for the Siemens- 
Martin process. 

The furnace used in the Talbot process is of the Wellman 
tilting type, and pours the metal from a spout instead of 
running from an ordinary tap-hole. The furnace is charged 
with about 75 tons of molten pig-iron, and worked as usual 
with open-hearth types, red haematite being the usual agent 



MANUFACTURE OF MILD-STEEL 37 

for decarburizing. When the carbon has been approximately 
worked out, the furnace is tilted by hydraulic rams, and 
25 tons of steel poured out into ladles, and upon coming to its 
horizontal position 25 tons of molten pig-iron is added. By 
this means a base of 50 tons of molten metal is retained, 
oxidation takes place quickly, and a uniformity of material is 
obtained. The furnace can be poured every four hours, thus 
greatly increasing the output. 

All the methods of manufacturing mild-steel described are 
in common use, and each has its peculiar advantages and dis- 
advantages. The acid Bessemer process is quick, and with 
suitable pig-iron produces steel of a very uniform quality. 

With the basic Bessemer it is difficult to obtain uniform 
steel from successive " blows,"" as it is not easy to define or 
detect the end of the operations, on account of the necessity 
of the " after-blow."' 

The open-hearth processes are slow, but much more under 
control, as the metal can be tested to make sure of the exact 
grade or percentage of carbon. A control is not possible in 
the fast, fierce Bessemer processes. By the basic open- 
hearth process a milder steel can be obtained than by any 
other. Owing to the difficulty of producing a steel of uniform 
quality by the Bessemer converter, the open-hearth process 
appears to be rapidly gaining favour amongst manufacturers. 

Mild-steel, when rolled, is inclined to honeycomb or pipe, 
owing to the separation of bubbles of gas in the cooling metal. 
To overcome this, pressure is sometimes resorted to. Sir 
Joseph Whitworth introduced the idea of subjecting ingots 
during solidification to hydraulic pressure, varying from 6 to 
20 tons per square inch, which compresses the ingot IJ inches 
per foot. The resultant steel is tough and homogeneous, and 
is termed " Whitworth fluid compressed steel."" The Krupp 
firm employ liquid carbon dioxide for the same purpose. The 
ingot moulds are covered with gas-tight covers connected with 
a reservoir of liquid carbon dioxide, and on warming the 
reservoir enormous pressure is exerted on the ingot. 



38 METAL-WOUK 

Use of Spiegeleisen and Ferro- Manganese. — Spiegeleisen and 
ferro-manganese are alloys of iron with manganese. When 
the percentage of manganese does not exceed 30 per cent, the 
alloy is known as " spiegeleisen " (German = mirror iron), but 
when 30 to 80 per cent, manganese is present it is known as 
" ferro -manganese. "" Both alloys contain about 7 per cent, 
carbon. In all processes for making mild-steel, spiegel or 
ferro (the common contractions of their names) is added, first 
to remove any oxygen, and secondly to supply the necessary 
amount of carbon. 

The principal uses to which m.ild-steel is applied are railway 
rails, boiler, bridge and ship plates, girders, roofs, rivets, 
bolts, nuts, and general constructional materials. 



CHAPTER VI 
MANUFACTURE OF CAST-STEEL 

In olden days steel was probably produced by accident and 
called " iron/" Indeed, it is difficult to see how it could be 
otherwise, and many ancient writers on chemistry looked 
upon steel as a particularly good or pure form of iron. Later 
this particular brand of " iron "" was proved to be produced 
by the addition of carbon. 

Cast-steel is probably, from the craftsman's point of view, 
the most important of all the metals, as it is the only one 
which can be readily hardened and tempered. These qualities 
make it particularly suitable for the present-day cutting 
tools, whilst it is also valuable for springs. Its hardness and 
homogeneity also make it an ideal material for measuring 
and most instruments of precision, such as rules, gauges, 
guns, etc. 

Steel can be produced by the following methods : 

1. Direct from the ore. 

2. By fusion of iron with the addition of carbon. 

3. From cast-iron by the removal of carbon. 

4. By mixing cast-iron with less carburized metal. 

5. By exposing wrought-iron to the action of carbonaceous 
matter at a comparatively low temperature. 

This last method is probably the oldest direct method 
known, but its origin cannot be traced. It is known as the 
" cementation process.'" The furnace used is shown in Fig. 9, 
and consists of two square converting pots or boxes formed 
of fire-brick slabs, and a narrow fire-hearth, about 15 inches 
wide, running the whole length between the boxes, with a 

39 



40 



METAL-WORK 



firing door at each end. The whole is covered by an arched 
roof, through which small chimneys project, usually three to 
each side. The " boxes '' are from 2 feet 6 inches to 4 feet 
deep, and slightly longer than the stock size of bars to be 
treated, which are usually about 10 feet long, 3 inches wide. 




Fig. 9. — Crucible Steel Furnace. 

and f inch thick. The charge is about 5 to 6 tons per box, 
and the loading consists of a covering of pieces of charcoal 
about the size of marbles, from which the dust has been care- 
fully sifted, covered in turn by a layer of bars J inch apart. 
Alternate layers of charcoal and bars are added until the box 



MANUFACTURE OF CAST-STEEL 41 

is filled to within 2 inches of the top. This remaining space is 
filled with " wheelswarf/' which is a grindstone mud of sand 
and rusted iron. The manholes, through which the charge 
was admitted, are now bricked up, the tap-holes prepared 
with fireclay, and the fire lighted. As no very great heat is 
required, sufficient draught is formed by the 40-foot chimney 
into which smoke and gases pass. In about twenty-four hours 
the boxes are a dull red, at which temperature the wheelswarf 
fuses and forms a coarse glass, hermetically sealing the boxes 
and preventing the passage of air. In another twenty-four 
hours a bright red or yellow heat of 2,000° F., and known as 
"cementation heat,'" is attained, and maintained for the time 
necessary to complete the carburization of the iron. The 
time varies from seven days, required for spring-steel, to eight 
days for shear-steel, and nine or ten days for high-carbon 
steel. 

From time to time trial bars are withdrawn through the 
tap-holes at the ends of the boxes. When the required state 
is attained, the fire is removed and the furnace allowed to cool. 
This process of cooling occupies about two days. Although 
the bars retain their original shape, the fibrous structure has 
given place to a granular or crystalline natm:e, and the surface 
is covered with "blebs'" or " blisters ■'"' (hence the name 
" blister-steel ""). This type of steel is more fusible than 
wrought-iron. 

Blister -steel contains carbon up to 1"5 per cent., the amount 
varying according to the time it was in the cementation 
furnace. It is never homogeneous, the siu-face being more 
highly carburized than the inner portion of the bar. Indeed, 
it is fairly common to find a bar with a wrought-iron core, and 
steel on the outer part, the one merging into the other 
gradually. Blister-steel, as such, is not suitable for practical 
purposes, but when faggoted, reheated, rolled, and hammered, 
it forms " shear -steel,'" and a repetition of the heating and 
rolHng forms " double-shear '' steel. This treatment slightly 
reduces the percentage of carbon, and leaves the metal more 



42 METAL-WORK 

uniform in quality, and quite suitable for such articles as 
large knives, scythes, shears, etc. 

The two changes that have to be accounted for are, first, 
the combination of the carbon with the iron, and, second, the 
cause of the formation of the blister. It must be remembered 
that the chief changes occur in the cementation furnace, the 
" crucible-steel " process being employed chiefly to obtain 
uniformit}^, which, as we have already noticed, is lacking up 
to that stage. 

At the temperatures of the furnace, the carbon of the charcoal 
combines with the oxygen of the air retained in the trough, 
forming carbon monoxide. At red-heat iron is very easily 
permeated by this gas. In fact, some authorities contend 
that in this state iron is capable of absorbing eight times its 
volume of carbon monoxide. It is also possible that carbon 
is absorbed by simple process of solution in the iron. 

The formation of blisters is probably due to the production 
of gas within the iron, by the combination of carbon with 
oxygen from the particles of oxide of iron of the bar. This 
gas, being imprisoned in the tenacious metal, would raise it 
into bubbles or blisters. 

Crucible-Steel. — To produce a regular and uniform metal 
from blister-steel. Huntsman, in the year 1740, introduced the 
practice of melting down blister-steel in graphite crucibles, 
and casting the molten metal into "ingot moulds ^^; hence 
the name " cast-steel.^^ The ingots are afterwards rolled into 
suitable bars, and are usually employed in the best cutlery 
manufacture. The furnace employed is shown in Fig. 10, 
and is similar to that employed in brass-melting. The fire- 
clay crucibles are usually about 16 inches high and 6 inches 
diameter, and two are placed in each furnace. After being 
heated to redness, each pot is charged with from 40 to 
50 pounds of carefully- chosen blister-steel, and the fire made 
up with hard fuel. In about forty-five minutes the fire will 
require remaking or making up, and in about another forty- 
five minutes the metal will begin to melt. The fire is re- 



MANUFACTURE OF CAST-STEEL 



43 



plenished a third time, and this heat brings the contents of 
the pots to a fluid state. The crucibles are now taken from 
the furnace by curve-nosed tongs, the scum or slag carefully 
removed from the surface, and the whole allowed to stand 
tranquil to free the metal from vesicles. The metal is then 
poured into ingot moulds. If large ingots are required, the 
contents of several crucibles are first poured into a ladle 
similar to that described in the Bessemer process. The ingot 
is now either kept hot in a soaking-pit or reheated when 



^ . Loose Covers 
Floor Lme S( 






■ 




a 


w 


■ 


Flue 


1 


■w^^ 


11 


Arch Over— 


■ 


Metal ' 
Door J 


1 


w 

1 



I Ground 

Line 



Fig. 10. — Crucible-Steel Furnace. 



required, and rolled to the necessary form and size. Great 
care must be taken at this stage to obtain a uniform heat, as 
if the metal is overheated the quality deteriorates, and the 
finished material is brittle or " burnt.'' The whole process 
occupies about five hours. 

The grade of a cast-steel depends upon the percentage of 
carbon it contains, but the quality depends upon many 
different conditions, such as freedom from sulphur, burning 
(due to overheating before rolling), piping in rolling, etc. 



44 



METAL-WORK 



Thus grade and quality do not necessarily run together. 
Steel of any grade may be good or bad. 



Grades of Cast-Steel. 



No. 


Name of Grade. 


Percentage of 
Carbon. 


Characteristics and Uses. 


I 

2 

3 

4 

5 
6 


Die temper 

Sett temper 

Chisel temper 
Pmich temper 

Turning-tool 
temper 

Razor temper 


0-750 

0-825 

1-000 
1-125 

1-250 

1-500 


Very tough. Capable of withstand- 
ing very great pressure. Used for 
snaps, hammers, pressing dies, 
and for welding to axes and plane- 
iron faces. 

Hard, strong, and tough. Capable of 
resisting sudden shocks, blows, etc. 
Used for cold setts, swages, fullers, 
flatters, rock drills, etc. 

Easily forged. Used for chisels, large 
punches, taps, shear blades, hot 
setts, etc. 

Hard, fine-grained metal. Holds a 
good cutting edge. Used for wood- 
working tools, drills, taps, and 
screwing dies. 

Quite unweldable, and requires care- 
ful treatment in forging. Used 
for lathe tools, drills, files, milling 
cutters, etc. 

Can only be forged by very experi- 
enced workmen, as if overheated 
it is useless. Not suitable where 
any sudden vibrations or varia- 
tions in pressure occur. Capable 
of very high temper and very keen 
edge. Used for razors, surgical 
instruments, etc. 



Self-hardening steels are obtained by alloying the fused 
blister-steel with small percentages of different metals : 



Name. 



Nickel steel 
Chromium steel . . 
Tungsten or mush- 
et steel 



Added Metai. 



3 per cent, nickel 

4 ,, chromium 
2-5 ,, tungsten 



Uses. 



Making of armour plates. 
,, projectiles. 

,, tools. 



MANUFACTURE OF CAST-STEEL 45 

Other brands are marketed containing vanadium or molyb- 
denum in small percentages. 

These steels are all self-hardening — that is, they do not 
require heating and quenching, as heating has not the same 
effect on them as it has upon ordinary cast-steels. They are 
therefore very suitable for high-speed cutting, there being no 
'' temper " to draw. 

Wootz is an extremely hard and elastic cast-steel prepared 
by the natives in India. It is made from small pieces of 
malleable iron, which are placed in small clay crucibles with 
about 10 per cent, of pieces of the wood of Cassia auriculata. 
The pots are heated on a charcoal hearth until the metal 
(only about 1 pound of which is in each) is melted. Faraday 
found aluminium in a sample of this steel, and was disposed 
to attribute its superior quality to the presence of this metal, 
but the analysis of specimens carried out later shows that 
aluminium is not always present in wootz. 

Puddled Steel can be produced in a puddling furnace by 
arresting the process before decarburization is complete. 
The steel thus produced is very poor in quality; for whilst a 
good steel is between pig-iron and wrought-iron for percentage 
of carbon, it is much purer than either. Only with remarkably 
pure pig-iron is it possible to obtain good puddled steel. 



CHAPTER VII 
THE ALLOY METALS AND THEIR MANUFACTUEE 

Copper. — Copper occurs in the metallic condition to a con- 
siderable extent^ and also in the form of easily reducible ores. 
Authorities are almost imanimous that it was the first metal 
used by man. Two processes of extraction from the ore are 
in use — namely^ the wet process and the dry process — but by 
far the greater quantity is obtained by the latter method. 

In extracting copper from its most common ore (copper 
pyrites), w^hich contains on an average 12 per cent, copper, 
the object of the treatment is to remove sulphur and iron. 
This is done by oxidizing off the sulphur as sulphur dioxide, 
and getting rid of the iron in the form of a fusible slag. The 
form of furnace used is shown in Figs. 11, 12, and 13, the 
latter being the latest type. 

The whole process of extraction is divided into six divisions, 
as follows : 

1. Calcination of the ore. 

2. Melting for coarse metal. 

3. Calcination of coarse metal. 

4. Melting for fine or white metal. 

5. Roasting of fine metal for blister-copper. 

6. Refining and toughening. 

1. Calcination may be carried out by roasting in heaps or 
kilns, as in the case of iron ore, or in a reverberatory furnace 
such as is used for wrought-iron. This latter is the commonest 
method. The charge consists of about 3 tons of crushed ore, 
which is roasted from twelve to twenty-four hours as required. 

46 



THE ALLOY METALS 



47 



During the process quantities of sulphur dioxide are evolved 
in the form of white fumes, known as " copper smoke/' These 
fumes are now used in the manufacture of sulphuric acid, 
instead of being allowed to escape, to the injury of the sur- 
romiding country, as was formerly the practice. 

During this first process the copper and iron sulphides are 




SECTION ON A.B. 




Fig. 11. — -Copper Furnace. 



partially converted into oxides. The calcined ore is now in 
the form of a black powder, which is raked out of the furnace. 

2. This powder is placed on the hearth of a second rever- 
beratory furnace, sometimes with the addition of slag derived 
from the fine metal, and is melted down by a more intense 
heat than that of the first roasting. 

A " matt '' of coarse metal forms on the bottom, and con- 



48 



METAL-WORK 



tains about 30 per 
cent, copper and 
sulphur, covered 
with fusible slag 
consisting of sili- 
cate of iron, and 
combined with not 
more than 0-5 per 
cent, of copper, 
called "ore- 
furnace slag/' 
After skimming off 
the slag, the matt 
of "coarse metal"' 
is run into water 
and thereby granu- 
lated. The roasted 
ore, it will be 
remembered, con- 
sisted of sulphide 
of iron and copper 
and oxide of iron 
and copper. When 
these are melted, 
the affinity of 
copper for sulphur 
is so great that all 
the oxygen com- 
bined with copper 
is transferred to 
the iron in ex- 
change for sulphur . 
3. The granu- 
lated or coarse 

Fig. 12. — Round Water - Jacketed Copper nietal is again cal- 
Blast-Furnace. cined. This pro- 




THE ALLOY METALS 



49 



cess lasts about twenty- 
four hours, during which 
time a large proportion 
of the sulphides are con- 
verted into oxides, the 
changes being similar to 
those of the first roast- 
ing. 

4. A charge of roasted 
coarse metal is again 
melted, together with a 
small proportion of 
copper ore known to 
be free from iron and 
sulphur, and rich in 
oxides and silica. The 
slag this time absorbs 
most of the iron, and 
the oxygen from the 
added ore helps to dis- 
place the sulphur from 
any remaining iron 
sulphide. The matt 
from this process con- 
tains about 60 to 70 
per cent, of copper, and 
is known as "fine"" or 
" white " metal. 

5. The " white '^ or 
"fine "' metal has now 
to be freed from sulphur, 
which is done in a rever- 
berator y furnace sup- 
plied with an oxidizing 
atmosphere. It is sub- 
jected for several hours 




Fig. 13. — Sectional Elevation of 
Fig. 12. 

4 



50 METAL-WORK 

to a heat just below that required for melting, when part of 
the sulphur is removed, with the formation of copper oxide. 
The product is then fused, and appears to boil, due to the fact 
that when copper sulphide and copper oxide are heated 
together they decompose each other, and produce metallic 
copper and sulphur dioxide. The appearance of agitation is 
produced by the escape of sulphur dioxide from the molten 
metal. When this agitation ceases, the metal is free from 
sulphur, although still containing 2 to 3 per cent, of impurities, 
chiefly iron and other metals. 

The metalhc copper sinks to the bottom, and the slag is 
drawn off. The copper is afterwards run into sand moulds 
and cooled off. These castings are full of cavities or bubbles, 
which give rise to the term " pimple " or " blister " copper. 

6. To remove the 2 to 3 per cent, of impurities, the copper 
is finally subjected to a refining process. About 10 tons of 
bhster-copper is melted down in a furnace and kept liquid 
from fifteen to twenty hours, air being allowed free access; 
the slag is skimmed off from time to time, and the remaining 
impurities removed. A small percentage of oxygen remains 
as copper oxide, which, if not removed, renders the metal 
brittle. This oxide is removed by plunging a pole of green 
birchwood into the molten metal, the inflammable gases from 
which produce a powerful agitation of the mass, thus assisting 
in the separation of any slag, and at the same time reducing 
the oxide present to metalHc copper. When the movement 
of the metal ceases, the refiner takes a sample to test for 
toughness. If his experience decides that the metal is tough- 
ened, the copper is tapped into iron moulds. If "over- 
poling " has taken place, the metal is almost as brittle as if || 
unpoled, and has to be exposed to the air for some time to 
bring it back to " to ugh -pitch.'' 

A small percentage of phosphorus, even so low as 0-5 per 
cent., reduces the melting-point of copper, and when cast in a 
chill mould increases its tenacity. It also acts as a protection 
against the action of sea- water. 



THE ALLOY METALS 51 

Lead. — The first mention of lead is in the Book of Numbers, 
being amongst the spoils taken from the Midianites. It is 
seldom found free in nature, although native lead does occur 
in small quantities in certain lead ores. The most common 
ore of lead is "galena/' or lead sulphide. 

There are many processes in use for smelting lead ores, all 
depending more or less on the same principles, but differing 
in the type of furnace used. Perhaps the commonest is the 




Fig. 14. — Flintshire Lead Furnace. 

Flintshire furnace, which is shown in Fig. 14. It is of the 
reverberatory type, and has a fairly large hearth, with a bottom 
of grey slags obtained from previous smeltings. This type 
of furnace has been used in North Wales from very early 
times. The ore is first washed to remove the lighter portions 
of the rocky matter, or gangue, which it contains. After 
heating the furnace to a dull red, a charge of about 1 ton of 
washed ore is introduced through the hopper. This is evenly 
spread out and roasted for about two hours, free access of air 
being allowed. Great care must be taken not to raise the 
temperature sufficiently to cause the ores to fuse. During 
this roasting much sulphur burns off as sulphur dioxide, and 



52 METAL-WORK 

lead oxide and sulphate are formed, but part of the galena 
remains unchanged. 

The temperature is now raised, and the lead begins to flow 
slowly from the ore. As the heat increases, the reaction 
between the sulphide, oxide, and sulphate, causes the lead to 
run freely, although the temperature is still insufficient to 
melt the rocky matter in the galena. A further rise of tem- 
perature causes the gangue to become soft and pasty, and to 
prevent its fusion lime is thrown into the furnace, which cools 
and stiffens it. It is now said to be ■" set up,"' and the heat 
is regulated so that the gangue is sufficiently stiff to resist 
melting diu'ing further calcination. When calcination is 
complete, the temperature is raised and the charge " flowed.^' 
At this point a small quantity of fine coal is thrown into the 
liquid metal, the gases from which burn and keep the metal 
in a liquid state during the " drawing-off "" or " flowing '' 
process, the charge being run into cast-iron basins. After 
drawing off the metal, any unreduced materials are again set 
up with lime and raked out as a grey slag. The time occupied 
by this process is about six hours, and if the " charge "" con- 
sisted of 1 ton of galena, about 14J hundredweights of lead 
will be obtained, which is only 80 per cent, of the total amount 
contained in the ore. The remainder is combined with the 
slag, and is almost completely recovered when the slag is used 
as a lining for the hearth during subsequent smeltings. The 
process gets its name of " air reduction " from the fact that 
no reducing agents are used. When the temperature is raised, 
the oxide and sulphide decompose each other, as in the reduc- 
tion of copper, and the lead separates. 

Lead produced by the air -reduction process contains, 
besides silver, a small amount of iron, arsenic, antimony, and 
copper. These are sometimes removed by melting the lead in 
a shallow reverberatory furnace, when the less fusible metals 
come to the surface as dross and are removed, leaving a 
refined lead. This process is modified in many ways in 
different parts of the coimtry, according to local requirements. 



THE ALLOY METALS 



53 



but the principle is always the same. In the North of England 
a slag-hearth is used^ as shown in Fig. 15. This may be taken 
as a type of small blast-furnace. This type of furnace is very 
common in America^ but is used in Great Britain chiefly for 
poor ores, limestone flux and coke being employed to free the 
lead. 

Galena always contains a certain amount of silver, which 
can be profitably extracted even when amounting to only 
2 ounces to the ton, owing to the fact 
that all the silver can be concentrated 
into a small portion of the lead by 
crystallization. Lead free from silver 
always separates out in crystals, 
leaving a rich alloy. This alloy, 
frequently containing from 300 to 
700 ounces of silver per ton, is then 
cupelled. Cupellation was the original 
method of extracting silver, and was 
not profitable where the percentage 
was small. By this process the whole 
of the lead is oxidized on a porous 
hearth, and the oxides 
(litharge) sink through 
the bed whilst the silver 
remains. This litharge 
is then again reduced 
in a furnace, with coal, 
to metallic lead. 




Tuyere 



Fig. 15. — Lead Slag-Hearth. 



Tin. — In order to prepare tin from its ores (tinstone or tin 
dioxide), the ore is first crushed, and then washed to remove 
the gangue. This is frequently done by running water, and 
is termed " tin-streaming.'" It is then roasted to eliminate 
arsenic and sulphur. This roasting, which is done in a 
reverberatory furnace, converts a large proportion of any 
sulphides which may be present into oxides, and changes the 
ore into a yello^vish-brown powder. This is again washed. 



54 METAL-WORK 

when the light oxides are removed and a refined tin oxidiB 
(black-tin) left. The " black-tin '' is then mixed with about 
one-fifth to one-eighth of its weight of powdered anthracite 
or coal-slack and a small quantity of lime. This mixture, 
which is sprinkled with water to prevent the finely powdered 
ore being drawn by the draught into the chimney, is then 
charged into a heated reverberatory furnace, and kept at a low 
temperature for some time, to allow for the reduction of the 
impurities. The temperature is then increased and the 
charge well stirred. After about six hours the mass is well 
fused, and the lime, combining with the gangue, forms a very 
fusible slag known to the smelter as " glass,^' and metallic tin 
gathers at the bottom of the bath. The slag is raked out 
and the metal ladled into moulds. At this stage the metal is 
known as " crude tin.'" 

The refining of " crude tin " involves two operations, known 
as " liquation '" and " boiling."' 

Liquation. — In this process about 18 tons of crude tin in the 
form of pigs, each weighing 4 hundredweights, are carefully 
heated to melting-point on the sloping bed of a reverberatory 
furnace. The purer tin, being most fusible, gradually melts 
out, and is run off into a cast-iron pan, leading an impure 
alloy of tin, iron, and arsenic, which is afterwards worked up 
to remove the tin. The purified metal is now heated in the 
pan into which it ran from the furnace, and is " poled "" or 
stirred with a pole of green wood. The dross, which separates 
during refining and contains quantities of tin, is worked up 
with the alloy of the liquation process, and the purified tin is 
cast into moulds. To test the quality of the product, the bars 
are heated to a temperature slightly below its melting-point, 
and hammered, or are dropped from a height. If pure, the 
tin splits into granular strings, and is sold as " grain-tin,"" the 
second quality being termed " block-tin."" 

The chemistry of the process is simple. Tinstone always 
contains a little arsenic, iron, copper, and sulphur, and these 
are oxidized in the preliminary roasting. In the smelting of 



THE ALLOY METALS 55 

the roasted ore, or " black-tin/' the tin oxide is reduced by the 
carbon of the anthracite or coal. The chemical action of the 
poling in the case of tin is somewhat uncertain, as the metal 
is not in a state to require a reducing agent, as in the case of 
copper. Probably the action is chiefly mechanical, and the 
stirring enables the impurities, in the form of scum, to separate 
quickly. 

Tin-smelting in small blast-furnaces, as used for lead ores, 
is carried out in Banca, Malay Peninsula, and other places. 
Charcoal is used as fuel, and about 32 hundredweights is con- 
sumed for each ton of tin produced. The loss of tin in the 
slag is considerable, but the metal obtained is remarkably 
pure. 

Tin may be produced in a state of perfect purity by electro- 
lytic action. By this process a platinum basin is coated with 
wax, with the exception of a small portion of the bottom. 
This is then placed in a porcelain dish on a piece of zinc which 
has been amalgamated with mercury. The platinum dish is 
filled with a dilute solution of tin chloride (obtained by dis- 
solving commercial tin in hydrochloric acid), and the porcelain 
dish is filled with dilute hydrochloric acid (1 part of acid to 
20 parts of water), the whole thus forming a small self- 
contained electric battery. In two or three days beau- 
tiful crystals of pure metallic tin will form in the platinum 
basin. 

Zinc. — The preparation of zinc on a large commercial scale 
appears to have been first carried out in Great Britain. Zinc- 
works were established at Bristol about the middle of the 
eighteenth century, but no Continental works were founded 
imtil the year 1807, in which year some were opened at Liege. 
The chief ores of zinc are blende (zinc sulphide, ZnS) and 
calamine (zinc carbonate, ZnCog). 

The ore is first roasted in order to drive off the carbonic 
acid and water, and in the case of blende to convert the sul- 
phides into oxides. Zinc is one of the few metals which are 
obtained by distillation. The process now almost universally 



56 



METAL-WORK 



adopted is known as the " Belgian method of extraction/' and 
was invented in 1810. 

The roasted ore is mixed with charcoal or coal-dust in 
proportions of 2 to 1, and placed in retorts each holding 



1 Supporting 

Plate 




Fig. 16. — Zinc Distillation Furnace (Regenerative Type). 

about 40 pounds of the mixture. These retorts are made of 
fireclay, and forty to sixty are accommodated in each furnace 
(Figs. 16 and 17). The furnace consists of a vertical chamber, 
open at the front, with an arched roof. The back of the 

Condensed 
Zinc , Holder 




Oxide & 
Dust Receiver 



Fig. 17. — Section of Zinc Retort. 



chamber has projecting ledges, and the front is fitted with a 
cast-iron frame with suitable holes for carrying the retorts. 
The retorts when placed in the furnace have one end resting 
on the projecting ledge, and are supported at the fiont by the 



THE ALLOY METALS 57 

cast-iron frames, the mouth of the retort being outside. A 
condenser is fitted at the mouth of each retort. 

When the furnace is fully charged with retorts, the fire is 
started. At first brown fumes issue from the condensers, 
followed by the characteristic green-white flame of zinc, 
which continues as long as the distillation lasts. The total 
distillation occupies about twelve hours, but the liquid zinc is 
withdrawn from the condensers about every two hours. 
When distillation is complete, the residue is raked out of the 
retorts, and these are then recharged and the process recom- 
menced. The yield of zinc from ore containing 50 per cent, 
of metal varies from 30 to 35 per cent. About one-half the 
remainder is recoverable from the residue, but about 7' 5 to 
10 per cent, is lost, mainly as vapour. 

The Silesian process differs from the Belgian mainly in the 
shape and size of the retorts and condensers, the principle 
being similar. 

Commercial zinc always contains a little lead and iron, 
together with traces of arsenic. 

Aluminium. — Although not found in a native state, alu- 
minium is the most abundant of the elements, with the excep- 
tion of oxygen. It occurs in all clays and earths, and when 
in combination with oxygen is known in various forms, of 
which the ruby, sapphire, and corundum, are commonest. 
A fine granular species of corundum is in common use as 
" emery,'' and a crystalline form, known as " carborundum,'" 
is used for grinding stones, and is exceeded in hardness only 
by the diamond. 

The metal was first produced in 1827 by Wohler. His 
method was slow and expensive, and is now entirely super- 
seded by the electrolytic process. Wohler's method was 
improved upon by Bunsen and Deville, but these also failed 
to produce a commercial success, as the price of the finished 
product was prohibitive. Even in 1890 the world's production 
was only 40 tons, and the price about 10s. per pound, whereas 
the present price is about Is. 3d. per pound. 



58 



METAL-WORK 



The electric furnace used in the electrolytic process is 
shown in section at Fig. 18. It consists of an iron casing 
which is heavily lined with alumina. The anode is the carbon 
shown (in large furnaces the carbons are in rows), and can 
be moved up or down at will. At the commencement of the 
process the cathode is formed either by the furnace itself or 
by a small steel plate at the bottom of the cavity. This plate, 
if used, must be water-cooled to prevent it overheating and 
combining with the aluminium. A small quantity of alu- 
minium and cryolite is first placed in the furnace and fused 



Carbons with 
Copper Spacings 



Band for Terminals 
Charge Opening 



over 



Tapping 
Hole 




Studs for 
Terminals 



Carbon 
Lining 



Iron Casing 
Fig. 18. — ^ Aluminium Furnace. 



by the heat of the electric current, which is slightly over 
900°. This fused aluminium then becomes the cathode, and 
the furnace is filled with a charge of cryolite or bauxite, 
which is brought to a molten state. The aluminium oxide is 
decomposed, the oxygen escaping through the hole in the 
furnace lid, and metallic aluminium collects at the bottom 
of the furnace. As the metal is withdrawn through the 
taphole, more bauxite is added in small quantities as 
required. 



THE ALLOY METALS 59 

The metal is grey-white in colour, and is very light, having 
a specific gravity of 2-6 to 2-1, the specific gravity of rolled or 
hammered aluminium being 0-1 above that of cast metal. It 
does not oxidize in air except when impure or when highly 
heated, and melts at a temperature of about 700°. It is not 
acted upon by nitric acid, but is dissolved by hydrochloric 
acid. 



CHAPTER VIII 

ALLOYS 

The generally accepted definition of an alloy is that issued 
by the Committee of the Iron and Steel Institute, which 
defines the term as "A substance possessing the general 
physical properties of a metal, but consisting of two or more 
metals, or of metals with non -metallic bodies, in intimate 
mixture, solution, or combustion, with one another, forming 
when melted a homogeneous fluid/' 

The properties of alloys seem to bear very little relationship 
to the properties of the metals composing them. 

The fusing-point of an alloy is invariably below the mean 
of its constituents, and in some cases is even lower than its 
lowest component, as in solder. A mixture of 1 part of tin, 
1 part of lead, and 2 parts of bismuth, melts at 95° to 98° F., 
although the lowest melting-point of its constituents is that of 
tin, at 232° F. 

The electric conductivity of an alloy is generally lower than 
the mean of its constituents. The sj)ecific gravity also differs 
in most cases from the mean specific gravity of its con- 
stituents, being a little above or below that which is obtained 
by calculation. 

The colours of alloys differ to such a degree as to appear in 
no way controlled by the colour of the component metals. 
As an instance, a mixture of 5 per cent, of aluminium with 
copper gives a yellowish - coloured alloy, almost similar in 
appearance to 50 per cent, tin and 50 per cent, copper, whilst 
60 per cent, zinc and 40 per cent, copper gives a silver white; 
50 per cent, antimony and 50 per cent, copper gives a fine 
purple mixture termed " Regulus of Venus " metal. 

60 



ALLOYS 



61 



As a general rule, the compounds forming alloys are harder 
in combination than when taken separately, and the tensile 
strength and ductility are greater. 

The principal objects in alloying are — 

1. To improve fusibility (by lowering the melting-point). 

2. To harden or toughen. 

3. To give cleaner castings. 

4. To alter the colour. 

5. To give definite electrical resistance. 

6. To resist oxidization. 

Copper-Zinc Alloys. — An alloy composed of copper and zinc 
is known as " brass. "" The zinc has the effect of hardening 
the copper, and also of forming an easy-flowing alloy, which 

Composition of Copper-Zinc Alloys. 



Percentage 

of 

Co'p'per. 


Percentage 
of Zinc. 


Name. 


Properties. 


90-0 
80-0 
70-0 
66-6 
60-0 

50-0 

40-0 

30-0 
20-0 


10-0 
20-0 
30-0 
33-3 

40-0 

50-0 

60-0 

70-0 \ 

80-0/ 


Red brass 
Dutch metal 

Best brass or 
Bristol steel 

English standard 
brass 

Muntz metal 

Yellow brass 

White brass 

Imitation plati- 
num 


Very tough. This material is used 

for engine work. 
Very malleable. Fine yellow 

colour. 
Malleable, ductile. Rolls well. 

Casts and works well. 

Rolls well hot. Resists corrosion. 

Used largely for the sheathing of 

ships. Sometimes contains 1 per 

cent. lead. 
Does not roll or work well. Is 

used as spelter for brazing. 
Very brittle and short. 
rVery weak. Will only withstand 
\ slight pressure. Used for cheap 
I jewellery. 



produces sound, clean castings. The tensile strength of brass 
is increased up to 45 per cent, zinc, but after this percentage 
the strength drops rapidly, and the ductility increases up to 
30 per cent, zinc, after which the same rapid droj) is noticeable. 



62 



METAL-WORK 



The addition of 2 to 4 per cent, of iron increases the strength 
and hardness of this alloy over an alloy of equal proportions 
which contains no iron. 

Brass has a good yellow colour until the copper falls below 
45 per cent., after which it becomes silver white. The terms 
" high "" and " low "" as applied to brass refer to the quantity 
of zinc in the alloy. " High " brass contains 33 per cent, or 
more of zinc, and " low "" brass 20 per cent, or less. The term 
" tombacs " applies to brass containing over 70 per cent, 
copper. 

Copper-Tin Alloys. — Copper-tin alloys are termed ' ' bronzes."' 
Bronze was one of the chief " metals " of the ancients. We 
have the term Bronze Age, which applies, not to a particular 
division of time, but to a condition of culture. All the useful 
bronzes contain less than 33J per cent, of tin. As tin is added 
to copper the solidifying-point of the alloy falls rapidly, and a 

Composition op Copper-Tin Alloys. 



Percentage 

of 

Copper. 


Percentage 
of Tin. 


Name. 


Properties^. 


90-0 


10-0 


Gunmetal 


Strong. Fine grain. Yellow -grey- 
colour. Used previously for gun 
castings. Principal modem use, 
high-speed bearings. 


94-0 


6-0 


Soft gunmeta] 


Used for mathematical instru- 
ments. 


80-0 


20-0 


Bell - metal, or 


Hard, sonorous. Used for bell 






tam-tam 


castings. 


66-6 


33-3 


Speculum metal 


White colour. Capable of very 
high polish; therefore used for 
specula of telescopes. 



peculiar phenomenon is noticeable. As an instance, gun- 
metal with 10 per cent, tin solidifies at 1,000° C, except for a 
small portion remaining liquid until 770° C. is reached. A 
compound of 20 per cent, tin and 80 per cent, copper solidifies 
in three stages, and over 20 per cent, tin in four stages. The 
alloy is common in the form of coins, statues, etc. For this 



ALLOYS 



63 



latter purpose it is popular on account of its fine casting 
qualities, and because of its fine colour, both when new and 
when oxidized by the action of the atmosphere. One class of 
bronze contains about 0*2 per cent, of phosphorus, and is used 
for bearings of machines and telephone-wires on account of its 
hardness and tenacity. 

Tin-Lead Alloys. — Alloys of tin and lead are best known as 
" solder "" and " pewter.'^ These compounds are always 
harder than lead, and the melting-point of the combination 
is lower than either tin or lead separately. It should also be 

Composition of Tin-Lead Alloys. 



Percentage 
of Tin. 


Percentage 
of Lead. 


Name, 


Properties. 


66-6 
50.0 

80-0 


33-3 

50-0 

20-0 


Fine solder 
Tinman's solder 

Pewter 


Very low melting-point. 

Used for ordinary soldering of tin- 
plate. 

Used for measures, plates, drink- 
ing-cups, etc. 



noted that in solder the melting-point falls as the percentage 
of tin rises. These alloys are very malleable and ductile. 
Pewter was formerly largely used in the making of plates and 
drinking-cups, and is again coming into use for decorative 
purposes. 

Standard Alloys. — 

Composition of Standard Alloys. 



Composition. 


Name. 


Properties and Uses. 


Per Cent. 
Gold .. .. 91-66\ 
Copper .. .. 8-33/ 

Silver . . . . 92-5 \ 
Copper . . . . 7'5 J 


English standard 
gold 

English standard 
silver 


r Harder than pure gold, 
and used for English 
[ gold coinage. 

r Harder than pure silver, 
and used for English 
[ silver coinage. 



64 



METAL-WORK 

Composition of Standard Alloys (continued). 



Composition. 



Copper . . 

Tin 

Lead 

Lead 
Antimony 

Copper . . 
Zinc 
Nickel . . 



Copper 
Tin 
Zinc 
Lead 



Tin 
Zinc 



Silver . . 
Platinum 

Copper . . 
Aluminium 

Copper . . 

Tin 

Lead 

Phosphorus 

Iron 

Nickel . . 

Copper . . 
Manganese 
Zinc 
Aluminium 

Bismuth 

Tin 

Lead 



Per Cent. 
95 ] 

t } 

80 \ 
20 / 




88 
5 
5 
2 



50 \ 
50 j 



65 
35 



} 



50 
25 
25 



Name. 



Properties and Uses. 



Coinage bronze 



Type metal 



German silver 



/Harder than copper. Eng- 
\^ lish copper coinage. 



Statuary bronze 



Pattern alloy 



Dental alloy 



Aluminium 
bronze 



Phosphor bronze 



Manganese 
bronze 



Fusible alloy 
(Rose's metal) 



1 



/ 



Expands on cooling. 

Eine white metal. Used 
for cheap jewellery and 
cutlery. Good base for 
silver plating. 

Withstands the action of 
the atmosphere. Has 
very fine colour either 
when new or old. 
Makes good castings. 
Hard. 

Fairly hard. Casts well. 
Used for patterns which 
will be subject to hard 

. usage. 

Hard. Used in dentistry. 



/ Strong as mild-steel ; mal- 
\ leable; ductile; elastic. 



TMuch stronger than or- 
"! dinary bronze. Gives 
{ fine, clean castings. 



{Tough. Resists corrosion. 
Used for ship propel- 
lers. 

"Melts below boiling-point 
of water. Used for 
fusible plugs. Dis- 
covered in 1772 by 
Valentine Rose. 



ALLOYS 

Composition of Standard Alloys {continued). 



Composition. 



Copper . . 

Zinc 

Iron 

Lead 

Antimony 

Tin 

Copper . . 
Nickel . . 

Tin 

Antimony 
Copper . . 

Steel . . 
Manganese 

Steel . . 
Nickel . . 

Steel 
Chromium 

Steel . . 
Aluminium 



86 "\ 

14 / 

93 1 

7 / 

98 ^ 

2 J 



98-5) 
1-5/ 



Swedish iron with alu- 
minium ^^Vo to y J-o by 
weight 



Name. 



Delta metal 



White metal 



Cupro metal 



Britannia metal 



Manganese steel 



Nickel silver 



Chrome steel 



Aluminium steel 



Mitis metal (Nor- 
den Feldts) 



Properties and Uses. 



/Strong, but not malle- 
\ able. 



/Used for bearings in 
\ machinery. 

/Used for making rifle 
\ bullets. 



Used for cheap cutlery. 



rHard; tenacious; duc- 
\ tile. 

Is more tenacious than 
ordinary steel. Used 
for armour plates. 

j" Resists penetration to a 
\^ very high degree. 

r Considerably hardens 
-! steel ; produces better 
I castings than steel. 

Melts and flows easily. 
Gives sound castings, 
with all the properties 
of good forged iron. 



Effects of Alloying — Ti7i. — Always increases the hardness 
and whitens the alloy. 

Zinc. — Increases the fusibility, but does not decrease the 
hardness, unless used in very large percentages. 

It increases the malleability when the alloy is cold, but 
decreases it when hot ; thus brass high in zinc cannot be forged 
at red heat. 

Lead. — When used in small quantities increases the ductility 

5 



66 METAL-WORK 

of brass, thus making it more suitable for bending, bossing, 
repousse work, etc., but if added in large percentages it tends 
to make the brass very short and brittle. 

Bismuth. — Lowers the melting-point of nearly all alloys, 
but tends to cause brittleness. 

Phosphorus. — Causes greater fluidity, thus enabling sound, 
clean castings to be obtained. 

Nickel. — -Hardens alloys, and gives good wearing properties. 

Antimony. — Imparts a hardness to alloys, and has the 
remarkable property of expanding slightly on cooling. 

Alloys containing mercury are termed amalgams: those 
containing two metals are known as binary alloys, and those 
containing three as ternary alloys. The expression " ternary 
alloy "" is sometimes used loosely to indicate an alloy con- 
taining tin. 

Preparation of Alloys. — Alloys are generally prepared by 
first melting the component metal having the highest melting- 
point, then carefully stirring in the other metal or metals. 
When one of the metals is volatile, as zinc in brass, it is usual 
to totally immerse it in the metal already melted, so as to 
render it less liable to volatilization. Li mixing zinc in copper 
for brass there is a loss of about 2 per cent, of the zinc from 
this cause. 

In the manufacture of brass, it is common to first melt a 
small quantity of scrap-brass mixed with powdered charcoal, 
then to add the copper, and, when this melts, the zinc. 



CHAPTER IX 

WOEKSHOP USES, PROPEETIES, AND CHARACTER- 
ISTICS, OF THE COMMON METALS 

Cast-iron. — It has already been observed that cast-iron is 
marketed in two grades — white and grey. These can be 
readily distinguished b}^ the outside appearance. White cast- 
iron has a very smooth white skin, while grey is identified by 
its dark, rough appearance. The former is rarely used in the 
handicraft-room because of its extreme hardness, but the 
latter is softer, and therefore more suitable. 

All cast-iron has a hard skin, caused partly by the outside 
of the casting coming into contact with the air, which causes 
the free carbon to become chemically combined, and partly 
by the iron fusing and combining with the sand of the mould 
(silica), thus forming a glassy face. This hard face should be 
chipped off with chisels, or removed by pickling in sulphuric 
acid before filing, otherwise it is liable to damage the file. 

The most common defect in cast-iron is the presence 
of minute holes, called " honeycombing "" or " sand-holes." 
These are generally caused by shaking the casting boxes after 
the mould is ready for casting, thus causing loose sand to fall 
into the pattern prints. This sand, being free, mixes with 
the molten metal when it is poured into the mould. 

Blowing or blow-holes is another defect, which, if not so 
common, is more annoying, as it often occurs under the 
surface, and cannot be detected until considerable labour has 
been expended on the casting. It is caused either by defective 
ventilation or dampness in the mould. In the case of defective 
ventilation the air in the mould, being unable to get away 

67 



68 METAL-WORK 

when the metal is poured, becomes interlocked in the casting, 
and when dampness is present the resulting steam has similar 
effects. 

Cast-iron should only be used where it is not subjected to 
any tensile strain. In the equipment of the handicraft-room 
its principal uses are beds, headstocks and saddles of lathes, 
bodies of drilling, punching and shearing machines, soldering- 
stoves, surface-plates, and the bodies of the cheaper type of 
parallel vice. 

In the course of work it is suitable for chipping, filing, and 
turning exercises, paper-weights, surface-plates, bases of 
scribing-blocks, bodies of screw-jacks, etc. In such operations 
as drilling, filing, turning, or scraping, it is best worked dry, 
but may be lubricated during tapping. Cast-iron can be 
easily cast into required shapes, which is one of its great 
advantages; it is also fairly cheap. Its greatest disadvantage 
is its brittleness. A method sometimes adopted, especially 
with small cast articles, is to embed them in powdered iron 
oxides, such as pure red haematite or smithy scales, and keep 
them at a red heat for about three days, the product being 
known as " malleable cast-iron.^" During the process the 
carbon diminishes and the cast-iron softens. Good pure cast- 
iron, however, is necessary, and when the process is carried to 
extremes the carbon disappears, but not the phosphorus, and 
also there is uncertainty as to the depth of softness. 

Wrought-Iron. — Wrought-iron is not now so extensively 
used as formerly, it having been replaced by mild-steel. The 
principal commercial use to w^hich it is put is chain-making, 
on account of its unique welding properties. It is also used as 
the base metal in the manufacture of cast-steel. Wrought-iron 
is distinguished by its close-grained outside appearance and by 
its fine fibrous structure. It enters very little into the equip- 
ment of the handicraft-room, except for cutting-out blocks, 
steel-faced tinman's stakes, anvils, etc. In the course of work 
it is very suitable for early forge exercises, such as bending, 
drawing-down, and jumping-up, and should always be used 



PROPERTIES AND CHARACTERISTICS 69 

for the first exercises in welding. During the operations of 
turning, drilling, screwing, and tapping, the metal should be 
lubricated. 

Mild-Steel. — Good quality in mild-steel is denoted by a fine, 
even blue sheen or skin on the outside, and by crystals of 
even size showing at any fracture. Whilst all the market 
grades of mild-steel are suitable for handicraft purposes, it is 
well to remember that the Bessemer product is usually harder 
and more variable than other brands. It enters largely into 
the handicraft -room equipment, being used for bolts and nuts, 
rivets, mandrils and feed - screws for lathes, spindles for 
diilling-machines, levers for shearing and punching machines, 
anvils (with the addition of a cast-steel face), forges, forge- 
tongs, stocks (for stocks and dies), tap-wrenches, callipers, 
squares, stakes, folding-bars, screw and box of the cheaper 
vices, body of better-class vices, etc. 

In the course of work it is very suitable for filing, drilling, 
riveting, screwing, and tapping exercises, and for later forge 
work. Its properties of bending and working cold also make 
it suitable for wire-working and simple bent ironwork. 
During the operations of turning, drilling, screwing, and 
tapping, the metal should be lubricated. 

Cast-Steel. — The quality of cast-steel is shown by its 
fracture. Small, fine, even crystals, closely packed, denote 
good quality. It possesses the invaluable property of becom- 
ing intensely hard if heated to redness and plunged into water, 
the various grades between softness and extreme hardness 
being regulated by the temperature of the metal at the 
moment of plunging. It is therefore an ideal metal for the 
manufacture of cutting tools of all description. In the handi- 
craft-room equipment it is used for files, chisels, punches, 
shears, snips, saws, taps, dies, drills, lathe tools, cutting-pliers, 
dividers, scribers, etc., and on account of its excellent wearing 
properties it is very suitable for gauges and measuring and 
testing tools. In the course of work it is employed for 



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75 



PROPERTIES AND CHARACTERISTICS 71 

advanced forge exercises, on account of the extra difficulties 
encountered in working, and for opportunities of introducing 
hardening and tempering. 

Models made of cast-steel usually involve the operations of 
forging, filing, turning, grinding, hardening, and tempering. 
Amongst such models may be mentioned drills, centre-punches, 
scribers, chisels, lathe tools, snaps, rivet-setts, screwdrivers, 
etc. During the operations of turning, drilling, screwing, and 
tapping, the metal should be lubricated. 

Copper. — This metal is considered to be next in importance 
to iron. It can be readily identified, as it is the only metal 
possessing a deep red colour, which is best seen when a ray of 
light is reflected from a bright surface of the metal. Good 
quality copper is recognized by the fine, smooth outside 
surface of the sheet or bar, whilst overpoled or underpoled 
copper, which is brittle, is detected by a pitted or rougher 
surface. 

Copper oxidizes very slowly under ordinary atmospheric con- 
ditions, but if heated to redness it readily oxidizes to scales of 
black copper oxide, which detach themselves on plunging the 
metal into water, leaving a bright, clean metallic surface. It 
is sonorous, and very malleable and ductile. It forges well 
at a low red heat, but if heated to a temperature approaching 
its melting-point it becomes so brittle that it may be reduced 
to powder by a blow from an ordinary hand-hammer. Being 
very tough, it is difficult to work with cutting or rasping tools. 
When being filed it causes " pinning " to a remarkable degree, 
and unless care is taken to prevent this fault good work 
cannot be done, whilst much good work is often spoilt by 
sudden " pinning "" of the file. In turning and drilling, cleaner 
cuts are obtained by applying a thin lubricant, such as 
turpentine or soapy water. 

The malleability of copper makes it a most valuable metal in 
the handicraft-room. This property adapts it specially for 
hammering up into bowls, bosses, seams, or other shapes; but, 
like most other non-ferrous metals, it quickly hardens on 



72 METAL-WORK 

being hammered. To overcome this hardness, it must be 
frequently annealed as the work proceeds. A^Tien the shape 
is flat, as in a sheet about to be worked, it is usual to anneal 
by heating to a dull red and quenching in water; but when 
the shape of the work is not uniform, it will be found best to 
allow it to cool slowly, otherwise the uneven contraction of 
rapid cooling tends to develop edge-cracks. There is little 
or no difference in the softness of the metal when annealed by 
either process, the only advantage of water-cooling being the 
saving of time. 

In handicraft schemes of work, the property of malleability, 
together with its rich colour, makes copper very suitable for 
such models as ash-trays, photo-frames, calendar -frames, 
bowls, jugs, serviette-rings, and various other forms of applied 
art, as the articles can be enriched by engraving or simple 
repousse work. Whenever copper is used for articles which 
come in contact with food it should be tinned. The use of 
copper in the equipment of the handicraft-room is not very 
extensive. It is used for the working end of the soldering- 
bit, where its property of retaining heat and its afi&nity for 
solder make it very valuable. It makes good vice-clamps, 
and is sometimes used for mallets to be used on brass and 
bright steel or iron. 

Zinc. — Zinc, as will have been observed, is one of the most 
recently discovered metals. The ancients used brass exten- 
sively, but were not aware that it was an alloy of copper and 
zinc. The nearest they ever approached to this fact was the 
discovery that this substance or earth coloured copper yellow. 
In addition to bearing the name of " zinc,"" it is also known 
and quoted in the metal market as " spelter,"' and care must 
be taken not to confuse it with brazing-spelter, which is brass. 

It can be readily identified by its bluish-white colour. 
Commercial zinc is very brittle, a fault due to the presence of 
iron and sulphur as impurities. A good commercial zinc 
should not contain more than 1*5 per cent, of iron. An 
examination of a fracture will indicate the quaUty, as zinc 



PROPERTIES AND CHARACTERISTICS 73 

fairly free from iron shows the crystal faces smooth and 
bright, whilst a speckled appearance indicates poor quality. 
Long after the discovery of zinc as a separate element, its 
brittleness was against its wide use, until it was observed that 
a greater degree of malleability and ductility was imparted to 
the metal by raising to a temperature of between 100° and 
150° F., at which point it can be drawn into wire or rolled into 
sheets. Since this discovery zinc has been largely employed 
for roofing, packing-cases, pipes, etc. It is but slightly 
affected by the atmosphere, but on exposure it becomes coated 
with a film of white zinc oxide, which, being insoluble, protects 
it from further action. It is superior to tin for coating iron 
for outside use, and when so applied the process is known as 
" galvanizing,"^ and the product as " galvanized iron."' 

In the equipment of the handicraft centre, zinc is only intro- 
duced, in common with other soft metals, for vice-clamps 
(occasionally, however, oil-cans are made from it). In the 
scheme of work it is fairly useful. Being non-rusting, it is 
used for such articles as soap-boxes, trays, funnels, measures, 
etc. It can also be used for early lathe exercises, where it 
has the advantage of softness, and can readily be recast. 
Zinc has a good appearance when made into small articles 
and polished, as it finishes with the appearance of pewter or 
dull silver. A thin lubricant, such as turpentine or soapy 
water, gives the best results in turning and drilling. 

Zinc is almost the only common metal which has a distinct 
" grain,'" and this fact must be always remembered in setting 
out work. The folds and bends of the model must, if possible, 
be taken across the grain, as bending with the grain is apt to 
fracture the material. The direction of the grain is easily 
observable in the sheet. Like brass and copper, zinc is 
inclined to harden when hammered, but by heating to a 
temperature of 200° to 250° F., and allowing to cool slowly, 
the softness is restored. We have observed that by raising 
to a temperature of 100° to 150° F. the metal is more ductile 
and malleable, but it is also well to note that at a temperature 



74 METAL-WOKK 

of just over 200° F. it is so brittle that it may be powdered 
in a mortar. 

Brass. — This important alloy can be readily identified by its 
bright yellow colour. It is malleable and ductile, can be 
rolled into thin plates, drawn into fairly fine wire, and is also 
a very good casting metal. In the equipment of the handi- 
craft centre its only use is in machine bearings, small screws 
and rivets, but in the scheme of work it is invaluable. It 
casts, turns, files, rivets, and solders well, but requires care 
during forging or brazing. Its colour and nature render it 
suitable for an endless variety of models, and, being sonorous, 
it is very useful for chimes, bells, etc. The metal is usually 
worked without lubricant. 

Tin. — Tin can be distinguished by its colour, which is white 
tinged with yellow. It is soft, malleable, and ductile, but 
possesses little tenacity or elasticity. This metal makes a 
peculiar cracking noise when bent, called the " cry "" of tin. 
A remarkable feature of this " cry "" is that as the quality of 
the metal approaches purity the " cry "" increases, whilst it is 
asserted that absolutely pure tin gives no cry. Dr. Miller 
attributes this noise to the internal friction between the 
crystalline particles. 

Its malleability and ductility allow it to be beaten or rolled 
into very thin sheets, and " tinfoil "" is produced as fine as 
0-001 inch in thickness. It does not lose its lustre on exposure 
to the air at ordinary atmospheric temperatures, and this 
property is utilized in coating iron and steel, forming what 
is commonly known as " tin-plate."' Articles made of tin- 
plate can be beautified by treating with a mixture of dilute 
sulphuric and nitric acids, and afterwards coated with one of 
the various coloured varnishes for preservation. The crystal- 
line markings thus produced give to the material the classifying 
name of " moiree metallique.'" 

Tin enters very little into the equipment of the handicraft- 
room. Oil-cans, small boxes for storing nails, screws, or 



PROPERTIES AND CHARACTERISTICS 75 

rivets, guards for cogs and running wheels, are made of tin- 
plate, these being its only uses, unless the supply of solder 
can be classed as equipment. In the scheme of work, tin- 
plate is used for all preliminary soldering exercises. 

Aluminium. — This metal closely resembles zinc in colour 
and hardness, but it can be readily identified by its extreme 
lightness. It can be rolled or beaten into thin foil or drawn 
into very fine wire, and is very sonorous, and when struck 
emits a clear and sustained note. Aluminium does not 
oxidize in either dry or moist air, and casts well in either sand 
or metal moulds. To improve the appearance of small models 
made of this material, a fine frosted surface can be obtained 
by first cleaning with dilute hydrochloric acid, and afterwards 
boiling in a saturated solution of common salt and immediately 
lacquering. 

Aluminium cannot be soldered under ordinary conditions, 
consequently joints must be obtained chiefly by riveting or 
folding. In annealing aluminium, an even heat should be 
maintained, and the metal brought up to a temperature of 
about 300° E., and allowed to cool slowly. It does not 
oxidize or rust in air, and is therefore much in demand for 
cooking- vessels ; whilst its strength, combined with lightness, 
makes it useful in light engine building, motors, aeroplane and 
balloon fittings, and the fact that it is antiseptic renders it a 
most suitable metal for surgical instruments. 

It does not enter into the equipment of the handicraft 
centre in any form, but in the course of work its fine surface 
and stiffness make it a very suitable metal for such exercises 
as photo-frames, key-racks, match-holders, inkstands, etc. 

Lead. — Lead can be identified by its blue-white colour and 
its extreme softness. It can be rolled into fairly thin sheets 
and drawn into wire, but it possesses little or no tenacity or 
elasticity. Most of the lead of commerce is fairly pure. The 
purest is the softest, as any hardness or brittleness in the 
metal is due to such impurities as tin, iron, copper, or silver. 



76 METAL-WORK 

It contracts considerably on solidifjdng and cooling, and is 
therefore not suitable for casting. It welds well if the faces 
are fresh and clean, and lead powder can be moulded or formed 
into blocks by pressure. Dry air has no action upon it, but 
if exposed to air and moisture the surface becomes quickly 
covered with a film of hydrated basic carbonate of lead. It 
enters into the equipment of the centre only for vice-clamps 
and hammering-blocks. In the scheme of work it may be 
used for demonstrations, and also for practice in forging and 
casting. 



PART II 
TOOLS AND PROCESSES 

CHAPTER X 

VICES 

A VICE is the first necessity to a metal-worker's bench. 
There are many types and patterns, but they can be con- 
veniently divided into two classes — namely, the " leg "" and 
the " parallel/' 

The leg vice is the older form, and for many purposes is 
still the best. It consists, as is shown in Fig. 19, of a long 
leg or staple which is fastened to the bottom of the bench, 
or, if convenient, let into the floor; a shorter jaw fixed to the 
longer one by a hinge; a square threaded screw working into 
a long turned nut called the "box"'; a spring to force the 
jaws apart; a strap keyed to the leg, and fixed to the bench 
by bolts or coach screws ; and a handle for turning and tighten- 
ing. The whole arrangement is strong, and will withstand 
hard wear, and for such operations as chipping, cold bending, 
or heavy work, is first in favour. It is made chiefly of 
wrought-iron or mild-steel, with cast-steel-faced jaws. It 
has, however, one serious disadvantage. The loose jaw, being 
fixed by a hinge, must always move in the arc of a circle. 
The jaws are finished on the bevel (Fig. 20), and when holding 
thin work only grip with the top edge, whilst when opened 
to their maximum they only grip on the bottom edge. This 
fault means that the worker cannot depend upon truth or 
squareness of his fixing, which means so much to him in any 
filing operation. 

77 



78 



METAL-WORK 



Parallel Vices.— To overcome this fault, the parallel vice 
(Fig. 21) was designed. It is made of cast-iron, with cast- 
steel face-pieces screwed to the jaws. The back cheek is of 
saddle form, and allows the stem of the front cheek to slide 







Fig. 20. — Leg Vice Jaws. 



Fig. 19. 

through. This stem is three sided, and thus passes over the 
nut which is cast with the saddle portion. The screw is 
shouldered and pinned to the front or moving cheek. By 
this arrangement, and by keeping the stem of the moving 
cheek large, a rigid, parallel motion is obtained. 



VICES 



79 



An ingenious arrangement, called the " instantaneous grip/"* 
has become verj^ popular during the past few years, on account 
of the saving of time in screwing up and the convenience 




Fig. 21. 



with which work is fixed. By this'arrangement the jaws can 
be moved quickly either out or in, by pressing a small spring 
lever, and the ordinary screw arrangement commenced at any 




Fig. 22. 



point to give extra pressure. The " Parkinson Perfect 
Vice " is an excellent example of this type, and is illustrated 
at Fig. 22. 



80 



METAL-WORK 



Fig. 23 shows the nut and part of the screw in section, the 
nut being withdrawn or disengaged from the buttress-shaped 
screw. This is done by means of the rocking-bar D, one 
edge of which is pivoted at E, the other edge engaging in the 
groove F of the nut-shank. The bar D is rocked by the lever 
G. When it is desired to slide the jaw A quicker than by the 
screw, the screw-knob H and the lever are gripped as in the 
figure. This rocks the bar D and withdraws the half-nut 




Fig. 23. 



clear of the screw, thus allowing the pull or push action. 
Fig. 24 shows a piece of work being tightened in the vice. 
The jaw A having been slid into contact with the work, and 
the lever C released, the half-nut S engages with the screw 
K, and a turn of the screw by the lever L applies the grip. 

Vices are measured by the width of the jaw. A suitable 
size for handicraft purposes is 3| inches and 4 inches. In the 
equipment sixteen vices are as a rule required, and it is 



VICES 



81 



advisable to vary both the sizes and the types. These might 
be set out as eight 3J-inch jaw and eight 4-inch jaw for size, 
and for type four leg and twelve parallel. Where possible, 
about four of the parallel vices should be of the " instan- 
taneous grip " pattern. The Board of Education regulations 
specify 3 feet 6 inches as the minimum distance between the 




EiG. 24. 

vice centres. The height is a rather more difficult matter to 
arrange. The proper height, as stated in the chapter on 
Filing (p. 89), is that the work should be just above the 
worker's elbow ; therefore the top of the vice-jaw should be 
level with the elbow. As boj^s vary in height, and the vices are 
usually fixed to long benches, this is scarcely possible. If more 
than one long bench is to be used, the heights might vary by, 
say, IJ inches, which will solve to some extent the difiiculty. 

6 



82 



METAL-WORK 



It is better to fix the vices too high than too low. Low 
vices compel the students to stoop ;, which, in addition to the 
physical evil, causes a loss of power and command over the 
tools. On the other hand, the difficultj?^ of too high a vice 
can be overcome by keeping a number of small wooden plat- 
forms of various heights upon which pupils may stand. 

Hand- Vices. — The hand- vice, as shown in Fig. 25, will be 
found very useful for holding small tools, screws, rivets, and 





Fig. 25. 

pieces of metal, which cannot be held firmly or conveniently with 
the fingers. It is also most useful for holding small work under 
the drill, and prevents the work turning and cutting the hand. 
It will be observed that the hand- vice (Fig. 25) is of the 
leg vice type. The jaws are closed by turning the winged 
nut. A parallel form of hand- vice is now on the market 
(see Fig. 26), and is tightened by turning the handle. A 
convenient size is one with a 1-inch jaw. 



VICES 



83 



Vice Clamps. — The jaws of a vice are cut almost similar 
to a file, to secure a firm grip of the work. It will be seen 
that in fixing any soft metal or fine work the jaws must be 
covered, to prevent these cuts marking the surface. This is 
done by means of " clams "" or " clamps " (see Fig. 27). In 
size they are generally the length of the vice jaw, and in 
breadth they cover the whole of the serrated jaw of the 
vice, with an equal amount to turn over the cheek. They 
may be made of wood, leather, lead, copper, brass, zinc, or 





• Clamp 



Fkj. 27. 



tinplate — wood being generally used when working lead or 
aluminium; leather for highly polished work or fine screw 
threads; lead for zinc, copper, or brass; and brass, zinc, or 
tinplate, for bright iron or steel. 

Lead is convenient in that it is easily melted and recast 
when damaged or worn. Wood clamps are generally of 
bay-wood connected by a leather hinge. Brass and copper 
clamps should be made from y\-inch material, and zinc or 
tinplate should be of stout gauge. 



CHAPTER XI 
FILES, FILING, AND SCRAPING 

Files are the most important of the metal-working hand- 
tools^ as their actions are the first to be learned, and also the 
most frequently repeated. Very few models, indeed, can be 
made in metals which do not involve the use of these tools; 
therefore it is most expedient that the characteristics of the 
file should be mastered. When a tool is thorough^ under- 
stood, the best and fullest value of its action can be obtained. 

The shapes are numerous, and vary according to the opera- 
tion to be performed or the outline required ; and in equipping 
a handicraft-room it is most essential that a good assortment 
of files should be provided. 

The various kinds of files are distinguished by the following 

data: 

1. Length. 

2. Cut. 

3. Sectional form. 

Length. — This is always measured along the edge, the 
tang not being included. Lengths vary from 3 to 20 inches, 
but the more common sizes used in the handicraft-room are 
the 10-inch and 12-inch for heavy or coarse work, decreasing 
to 4-inch and 6-inch for finer work. The usual practice is to 
supply each student with one 12-inch bastard, one 10-inch 
bastard, and one 10-inch smooth fiat with safe edge, and to 
provide a general equipment of smaller sizes, finer cuts, and 
varied sectional forms, for occasional use. 

Cut. — This term relates to the degrees of fineness of the 
teeth, which are as shown in Fig. 28. As will be observed, 

84 



FILES, FILING. AND SCRAPING 



85 



the grades of cut vary considerably, but experience has 
proved that the bastard and smooth are sufficient for 
nearly all school handicraft ^Durposes. The number of teeth 
per linear or running inch is usually : 

Rou^h .. .. .. ..22 



Middle 
Bastard 
Second cut 
Smooth 
Dead smooth 



26 
32 
44 
68 
120 



\?'S 









Dead Smooth, 



i tiiii y^ , '"i ' { 



> .'" "til 



:s 



t / '> , ''"'1 



Smooth. 




Second Cut. 



m 
m 



Bastard. 




Middle. 
Fig. 23. — File Cuts. 




Rough. 



Note. — These sizes are taken on a 12-inch file. In the 
smaller sizes the number of cuts per inch is greater as the 
length diminishes. 

The teeth are formed by giving two separate sets of cuts 
along the material in such a manner as to form each tooth of 
diamond shape, the first set being at an angle of 55 degrees 



86 



METAL-WORK 



with the centre line of the file, and collectively known as the 
" first course '' or " over cut/' The second set of cuts form 
an angle of 80 to 85 degrees with the centre line, and are 
known as the " second course " or " up cut/' Single-cut 
files are termed " floats " or " float files/' their special use 
being the working of very hard metals, such as sharpening 
saws, knives, and cutters. 

Sectional Form. — There is a very large number of sectional 
forms in use, each designed for some particular type of work. 
The principal forms, however, are as shown in Fig. 29. 

Flat. — This class of file is always double cut on the faces, 
and single on the edges. The usual type now sold show the 



Flat. 



Half -Round. 



Square 



O 



Round. 




Tnangvilar. Knife -Edge. 

Fig. 29. — IPile Sections. 



edges parallel, thus giving a rectangular face, and its thickness 
parallel for two -thirds of its length from the tang end, then 
being drawn out, wedge-like, to a blunt point. It is also 
usual to leave one edge quite plain, or free from teeth. 
This edge is known as " safe," and is extremely useful 
where right-angle corners require filing without danger of the 
tool cutting into both faces together. The older form of 
" flat " files had a tapered face as well as edge, but this form 
is gradually being superseded by the "flat, safe and parallel." 

Half-Round. — This class of file is double cut on the flat 
face, but the " half-round " face receives a series of rows of 
single cuts from shank to point. As the rows intersect 



FILES, FILING, AND SCRAPING 87 

at differing angles, this gives the file the appearance of being 
double cut. It is usually parallel for about two -thirds of 
its length, after which it tapers both in width and thickness, 
but with its flat face always lying in the same plane. It will 
be noted by referring to Fig. 29 that the section is not semi- 
circular, but segmental. This file is always distinguished and 
ordered by its length and cut. 

Square. — The square file is double cut on all four sides, and 
is parallel for two-thirds of its length, when it begins to taper, 
but still retaining its square section. It can, however, be 
bought parallel through its whole length, when it is known 
as " parallel square."' When describing or ordering, always 
state length, cut, and size of square section. 

Round. — Made in the usual six grades, it can be obtained 
parallel, when it is termed " parallel round,"' but is usually 
tapered in its point third, when it is called a " rat-tail file."' The 
cuts are single, each row slightly intersecting, and from shank 
to point. The terms for ordering are length, cut, and diameter. 

Triangular or Three-Square. — This file is made in the usual 
six grades, and shows an equilateral triangle in section. It 
is usually of equal section for two -thirds of its length, and 
then tapers to a point. The sharp edges consequent upon its 
shape vary somewhat in sharpness according to the grade of 
cut. The ordinary metal-worker's three-square file differs 
from a saw file in that the latter has a series of cuts upon the 
sharp edge to form a slight roundness in the recess between 
the saw teeth. The type parallel throughout its length is 
called " three- square parallel." It is necessary to consider 
only length and cut when ordering. 

Knife-Edge. — This file is generally made in the smooth 
grade, with two large flat faces, which are double cut, and 
a small face or edge, which is single cut. The file is also 
parallel for two-thirds of its length, from which it tapers to 
a fairly fine point. The knife-edge file is distinguished by 
its length and cut. 



88 METAL-WORK 

Other files which may be termed fairly common are the 
warding, or ward, and the needle files. Ward files are seldom 
over 6 inches in length, 3-inch or 4-inch being the commonest 
size. They are of the same cuts as the flat files, but differ 
in that they are much thinner in proportion to their width, 
and are brought to a point instead of being parallel. Needle 
files are similar to round or rat-tail, except that they are 
usually 3 to 4 inches long, and very small in diameter, usually 
about |- to Yg- inch. These two types are distinguished by 
cut and length. 

Manufacture. — In file manufacture the bar is taken, and 
a blank cut off, forged, annealed, and ground smooth. After 
this the cutting of the first course is commenced at the point 
of the file, the chisel being held at angles varying with the 
degree of cut required, and is about 12 degrees for rough, 
10 degrees for bastard, 5 degrees for second cut, and 4 degrees 
for smooth. 

After the first face is cut, the file is held in position for 
the treatment of the other faces by setting in pewter or lead. 
The action of cutting leaves the file in a more or less bent 
shape, which has to be straightened; and as the action of heat 
is necessary to avoid danger of breaking, something has to 
be done to protect the fine portions forming the teeth from 
being destroyed, or even their fine edges damaged. The 
files are prepared by drawing them through some sticky 
substance, such as yeast, then sprinkling with common salt 
and hoof -parings. This process has been found to protect 
the teeth. The file is then heated to a dull red, and straight- 
ened by being struck with a lead hammer whilst lying upon 
two lead blocks. It is then reheated to a bright cherry red, 
immersed in water until nearly cool, and finally cooled off 
in oil. This last process preserves the teeth from rust. The 
tang must now be softened to prevent it breaking, and this is 
done by dipping it into molten lead. 

Most manufacturers now sand-blast the finished tools, to 
obtain a cleaner and sharper edge than that left by the chisel. 



FILES, FILING, AND SCRAPING 



89 



If possible, the handicraft instructor should obtain all shapes 
and cuts of files for purposes of observation by students, 
and also at least one set showing the various processes of 
manufacture. 

Filing. — The position of the work is most important in 
filing, and should be just above the worker's elbow. But 
as the work must also be firmly gripped in the vice, and not 
too high above the jaws, it is important that the top of the 
vice should be on the elbow level. 




Fia. 30. 



To hold the file, only one method is adopted for the right 
hand, and by referring to Fig. 30 it will be observed that the 
end of the handle is allowed to rest in the palm of the hand, 
and the fingers close round it, with the index -finger upon the 
top or along the side of the handle. Three methods are 
allowed of holding with the left hand, each with its peculiar 
advantage. These three methods are shown in Figs. 30, 31, 
and 32. For Fig. 30 allow the tip of the file to rest against 
the palm of the hand, and grasp firmly with the four fingers 
under the file. By this method the whole weight of the body 



90 



METAL-WORK 




Fig. 31. 




Fig. 32. 



FILES, FILING, AND SCRAPING 



91 




Left, Forward & Right. 



-1' 



Right. Forward & Left. 



can be comfortably applied to the file, and is used when a 
quantity of material is to be removed. 

For Fig. 31 place the two first fingers under the tip of the 
file, and the thumb on top. This method of holding is useful 
for lighter work and for small files, and allows a perfect com- 
mand for change of position or direction during the working 
of shaped or curved 

exercises, and also / / 

allows the file to be // / / 

applied in any par- 
ticular place. 

For Fig. 32 extend 
the thumb as far as 
possible from the 
fingers, and then 
place the hand on 
top of the file, with 
the extreme finger- 
tips at the end. By 
this method the run 
of the file can be felt, 
and any tendency to 
get the work out of 
the flat detected, 
whilst at the same time it allows a fair, even pressure. 
This method also allows the whole length of the file to 
be used. It must always be remembered that the file cuts 
on the forward stroke only, and it is during this stroke 
that the pressure must be applied, always proportionate to 
the size of the file and the work being done. Whilst it is not 
necessary to lift the file on the return stroke, no pressure 
should be applied, but rather a tendency to ease up the 
weight. 

As a flat surface is usually dealt with in the first operation 
in any exercise, care must be taken to obtain accuracy, or all 
other surfaces squared or measured from it will be equally 




v: 



Fig. 33. 



-o- 



92 



METAL-WORK 



out of truth. The usual tendency in filing flat surfaces is 
always to remove the edges, leaving a convex surface. By 
filing across the material at an angle of about 45 degrees, 
moving the file forward and sideways in one motion, occa- 
sionally reversing the direction from forward and left to 
forward and right, this fault is to some extent overcome 
(see Fig. 33). During filing operations, oil, grease, and the 
hands, should be kept from coming in contact with the surface 
of the work, as anything of a greasy nature causes the file 




Fig. 34. 



to slip rather than cut the material. When work has been 
" trued up,^' it should be finished by " di^aw-filing.'" For this 
operation hold the file as in Fig. 34, with both thumbs on the 
edge nearest the body, and the fingers of both hands on the 
other edge; then carefully push and draw the file over the 
work. This produces a series of parallel lines, or fine cuts, 
along the greatest length. Draw-filing should always be 
done parallel to the long edges. It considerably improves 
the appearance of work. Always remember the file is to be 
held by the finger-tips and thumbs only. Work can be 



FILES, FILING, AND SCRAPING 



93 



further finished by the use of emery cloth and oil after draw- 
filing, and surfaces thus treated withstand rust much better 
than those simply file- finished. 

It will be noticed that the file during filing becomes clogged 
by minute particles of metal interlocking between the teeth. 
This fault is termed " pinning/' and in effect it scratches or 
cuts the material, leaving faults very difficult to remove. It 
can be remedied by means of a wire brush, called a " scratch 
brush " or " file card/' being rubbed over the file in the 
direction of the " cuts.'" Any small particles not removed 
in this manner, by reason of their firm hold, must be picked 
out by a fine -pointed scriber. 
Pinning can be prevented to a 
large extent by chalking the file. 
This has also the advantage of 
improving the finish of the work. 
Files which are practically useless 
through grease, dust, etc., can be 
cleaned by boiling for a few minutes 
in strong soda water, scrubbing 
with a stiff brush, and finally 
rinsing in paraffin. There is con- 
siderable difference in the grip of 
a file on different materials, being 
least on zinc and brass, and greatest 
on wr ought-iron. 

Whenever possible, new files should be used for zinc, after 
which they are still in good order for brass, wrought-iron, 
cast-iron, and steel, in the order stated; but a file which has 
been used on cast-iron or steel is not afterwards effective 
upon brass or other soft metals. 

Scraping. — The object of scraping is to obtain a truer 
surface than is possible by filing. Scrapers are usually made 
from old files, preferably flat smooths, the ends of which are 
forged not greater than Jg inch thick. To harden, heat to 
blood red and plunge in water, so as to leave very hard. The 




Fig. 35.' — Sckaper Edges. 



94 



METAL-WORK 



scraping edge (Fig. 35) should then be ground slightly roiuid, 
and the two flat surfaces rubbed on a fine oilstone. The 
scraper is then prepared for setting the edge, which is done 
by rubbing upon an oilstone whilst the scraper is held in a 
vertical position. To test the cutting edge, try the scraper 
upon the thumb-nail, which it should pare with ease if in 
good order. 

To hold the scraper correctly, grasp the handle with the 
right hand, allowing the index-finger to stretch down the 




Fm. 36. 



blade underneath, as in Fig. 36; then place the left hand over 
the scraper, firmly grasping the tool and the index-finger of 
the right hand (see Fig. 37). The high parts of the work, 
which are to be scraped off, are discovered by rubbing on a 
standard surface plate which has been lightly smeared with 
red lead and oil, when patches of colour will be transferred 
from the surface plate to the work. These parts must be 
scraped down, and then rerubbed and again scraped. These 
two processes are repeated until the smeared or coloured 



FILES, FILING, AND SCRAPING 95 

portion covers the whole surface fairly regularly. As the 
work nears truth, the scraper must be kept very sharp and 
worked in short strokes. Upon completion with the scraper. 




Fig. 37. 



it is usual to rub the work lightly with an oilstone slip in 
places, resembling small regular scrapings. Examples of 
scraping and the truth of work may be found on the bed 
plate of any good lathe or surface plate. 



CHAPTER XII 

MEASURINa, TESTING, AND MARKING-OUT TOOLS 

T^He production of accurate work depends largely upon the 
standard reference of measuring, testing, and marking -out 
tools. It is essential, therefore, that they be of good quality, 
easy to manipulate, and capable of withstanding the heavy 
wear to which they are subjected in the handicraft-room. 

Rule. — -Wooden rules are not sufficiently accurate, nor are 
they suitable, for metal- working. The use of oil and the 
working of hot metals in forging would quickly render them 
useless. 

A 12-inch steel rule IJ inches wide and 3^^ inch thick will 
be found most convenient and serviceable. The markings 
should be " machine-divided,'" with the usual subdivisions of 
2, i, if and y\ inch throughout its length, and the first three 
inches again divided into ^^ inch. It should be made of best- 
quality cast-steel, hardened and tempered to spring temper 
to avoid the risk of " kinking.'' The edges should be true and 
parallel, so that the rule can be used for testing the flatness or 
truth of surfaces. A good rule with the points described can 
also be obtained with English measurements along one edge, 
and metric along the other, both on the same surface, which 
allows a comparison of the sizes. 

Whilst the metric system of measurement is, in Great 
Britain, not compulsory, but merely an alternative, it will be 
found most convenient in tinplate work to be used for scien- 
tific or experimental purposes. The transference from volume 
by measurement to volume by capacity is most convenient, 
as the quantities are all of one denomination. In most branches 

96 



MEASURING AND MARKING-OUT TOOLS 



97 



of metal-working the standardization of drills, stocks, dies, 
and materials, in English measurement compels the use of that 
measurement ; but wherever possible or convenient the metric 
system should be used, to allow students to become familiar 
with its use. 

A rule subdivided into tenths of an inch will also be found 
convenient, especially in circular work involving the use of cr. 
It will be generally found that the markings on a good English- 
made rule are deeper, and consequently last longer, than 
foreign-made or cheap English-made rules, and the difference 
in cost is only about IJd. per rule. 

Try-Squares. — A square with a 3-inch stock and 4j-inch blade 
will be found most convenient in the handicraft centre for 
students' use. These squares are made of mild-steel and in 
three different types. 



^u 



Separate Plates^, 






Fig. 38. 



1 ''' 
-^Q Rivets Spaced 

as Shown 



Fig. 39. 



The first and cheapest kind (Fig. 38) consists of a solid 
stock into the end of which a saw- cut is put. Into this cut 
is fitted the blade, and two rivets are used for fastening. The 
only recommendation for this style is its price, its fault being 
the danger of the rivets either not tightly filling the drilled 
holes, or loosening and allowing the tool to get out of truth. 

The second kind (Fig. 39) consists of three plates, two face- 
pieces being riveted to the angle piece to form the stock. 
This type is more reliable and is not easily damaged, but is 
slightly more expensive than the first kind. 

The third kind (Fig. 40) is forged from the solid, and is 
extremely acciu-ate. Standard squares used for testing work- 

7 



98 



METAL-WORK 



ing squares are of this type, one at least of which should be 
kept for very important work and for testing other squares. 
On account of the difficulty and time required in making, these 
are very expensive. 

The accuracy of working squares may be tested, in the 
absence of a standard square, in the following manner (Fig. 41) : 

First test the edges 
of the stock to find 
if they are parallel, 
and also the edges 
of the blade. Ob- 
tain a flat surface 
with a perfectly 
straight edge, and apply the stock of the square to the edge, 
and with a sharp scriber draw a line on the flat surface along 
the edge of the blade. Now reverse the square, and if the edge 
of the blade coincides with the scribed line the square is true. 




Fig. 40 



Position 2 



-f 



C 



Position 1 



Flat Surface 



Fig. 41. 

If the edge does not coincide, the square is out of truth to the ex- 
tent of half the angle the reversed square makes with the original 
line. After the first equipment of the centre, any replacements 
of this tool will form a good exercise for advanced pupils. 

Scriber. — The hand-scriber is employed for marking lines 
on metal, and is used in the same way as a pencil in drawing. 
The type used in handicraft centres is generally made of 
^\-inch diameter cast-steel, and is about 6 inches in length. 
One end is bent into a ring, and the other ground for J inch to 
a fine point. This point is hardened, but not tempered. 



MEASURING AND MARKING-OUT TOOLS 



99 




Fig. 42. 



No. 6 knitting needles will be found very suitable for making 
scribers for class use, and form a good early exercise in cold 
bending. At the same time it shows the nature of steel, as 
it must be softened to bend. If heated to soften over a 
bunsen, the polished surface of the needle gives a vivid example 
of the tempering colours. 

Centre-Punch (Fig. 42). — Two sizes are necessary in the 
handicraft-room. The larger is usually made of |-inch 
octagonal cast- 
steel, about 4|- 
inches long, with 
a 90 -degree 
point, and hardened and tempered to light straw. This size 
is used for marking main centres, centres of holes for drilling, 
and the ends of work for turning in the lathe. The smaller 
size is sometimes called the " dot " punch, and is made of 
J-inch octagonal cast- steel or 
J-inch round and knurled. It 
is 3 J inches in length, with a 
CO-degree point, and tempered 
to dark straw. It is used for 
confirming fine scribed lines, 
curves, or circles, by placing 
" dots " along the marking about 



J inch apart. Replacements of 
equipment can be made by 
pupils. 

Bell Centre-Punch (Fig. 43).— 
This tool is used for centering 
romid bars for lathe work. The 
work is fixed in an upright Fig. -iS. 

position, and the hollow cone or 

bell placed over the end, with the central axis of the punch 
kept in line with the central axis of the bar. By pressing 
the punch upon the work, the point automatically finds the 
centre of the bar. The tool is usually made of gunmetal. 





100 



METAL-WOKK 



and is measured by the maximum size of bar it will take. A 
convenient size is 1 inch. 

Callipers (Figs. 44, 45, and 46). — Callipers are generally made 
of good mild-steel. In some cases they are made of cast-steel 
with hardened and tempered points. It is questionable if the 
latter are as good as those of mild-steel, as the wear is very 




Fig. 44. 



Fig. 45. 



Fig. 46. 



little, and a better " feel '' is obtained by soft points. Three 
kinds are usually used in handicraft centres, and each about 
4 inches long. 

1. " Outside '" callipers, for obtaining the diameters of round 
bars, thickness of plates, and for testing parallel faces. 

2. " Inside '' callipers, for obtaining the diameters of holes, 
the distance between collars and shoulders, and testing the 
sides of holes for parallelism. 

3. " Jenny *' or " odd leg '' callipers, sometimes referred to 
as "compass," " scribing,'' or " centering " callipers. They are 



MEASURING AND MARKING-OUT TOOLS 101 



similar in construction to inside callipers, except that one leg is 
ground to a sharp point instead of being curved. This straight 
leg is made of cast-steel, so that the point can be hardened and 
tempered. The principal use of this tool is the marking of 
lines parallel to existing edges, scribing lines on work revolving 
in a lathe by holding the curved leg against the end of some 





Fig. 47. 



Fig. 48. 



finished shoulder, and for finding the centres of circular, 
square, rectangular, or polygonal bars or surfaces. 

Dividers. — Dividers are used for dividing or spacing out, and 
for marking out curves and circles. Two kinds are in common 
use in the handicraft-room : 

1. The wing compasses (Fig. 47), about 6 to 8 inches long, are 
opened or closed by pressure of the fingers and fine adjust- 
ment by tapping or knocking the leg. When the required 



102 



METAL-WORK 



size is obtained,, the movable leg is fixed to the projecting 
wing by the thumbscrew. They are suitable for larger work. 
2. The spring dividers (Fig. 47) are preferred for small 
work. The legs are joined by a spring which tends to throw 
the points apart^ and adjustments are made by a screw and 
nut. Except in small sizes, alterations and readjustments 
are slower, but the greater accuracy more than compensates 
for lost time. The sizes range from 3 inches upwards. 

Surface Plate. — The surface plate or plane table is made of 
close-grained cast-iron, with strengthening or stiffening ribs 




Fig. 49. — Standard Sueface Plate: Under-side, Showing Ribs. 

to counteract any tendency to twist or warp. Fig. 49 shows 
a Whitworth surface plate, which gives the best arrangement 
of ribs. It will be observed that the plate rests upon three 
bearing points when in use, thereby giving a steady seating. 
Surface plates are very expensive. This is due to the care 
and labour necessary to produce articles of truth and exact- 
ness. After the casting is obtained, the upper surface is first 
planed or filed, and then scraped to a perfectly true surface. 
This surface is either tested by comparison with an existirg 
standard plate of at least equal size, or by facing two other 



MEASURING AND MARKING-OUT TOOLS 103 

plates. This latter method depends upon the principle that 
" if three surfaces are mutually coincident, then each of those 
surfaces must be a true plane/' This can be demonstrated by 
taking three bars (say 8 inches by 1 inch by ^ inch) and purposely 
making them slightly concave. Mark the bars A, B, and C. 
Make A to coincide with B and G. It will now be found 
impossible to make B coincide with A and C without an 
all-round adjustment, which will be the first step towards a 
straight-edge. The fitting must be repeated, testing each one 
in turn with the other two, until all are perfect straight-edges. 
After an experiment with bars, the difficulties in truing sur- 
faces will be appreciated. 

In using the standard surface plate, a little red ochre or 
red lead mixed with oil is smeared over the plate, only enough 
being used to barely colour the surface. The work to be 
tested is then placed on the plate, and with a firm downward 
pressure drawn across it. Any high places on the work will 
show the colour. Each such place must be eased down with 
the scraper, and again tested and scraped until the surface 
is satisfactory. Great care should be observed in the handling 
and use of the surface plate, and students cannot be over- 
impressed with this point. Work should never be dropped 
or hammered upon it, nor should it be scratched. When not 
in use, the surface should be thoroughly cleaned, -then smeared 
with a little clean oil, and the plate kept in a box. 

In the handicraft-room a rectangular plate about 10 by 
6 inches or 12 by 8 inches will be found most convenient. 
A plate-glass sheet is often used as a substitute, but, whilst 
it has the advantage of not being liable to rust, its accuracy 
cannot be guaranteed. The surface plate is a splendid 
exercise in accuracy; but where a student is only attending 
the metal- work room for two or three hours per week, the 
large amount of labour required, combined with its monotony, 
is not calculated to arouse or stimulate the interest. For 
these reasons it is not a suitable model for schools, but the 
testing and truing might be done if necessary. 



104 



METAL-WORK 



Scribing Block. — The scribing block or surface gauge is used 
on the surface plate, and is for scribing a line parallel to a face 
or to another line, and for finding the centres of bars for 
turning. It can also be used for " feeling " surfaces for 
truth or parallelism. It usually consists of an upright pillar 
fixed to a heavy base, and a scriber carried in a sleeve which 
travels on the pillar. The base may be 
rectangular (Fig. 50), with a cut out of the 
under -face to reduce the bearing surface, 
or circular (Fig. 51). In the latter case a 
bearing surface of J inch width is left round 
the outer edge of the base, and the inner 
portion cut out. This is also to reduce the 
bearing surface, and so allow truth to be 
more easily obtained. The base may be 





Fig. 50. 



Fig. 51. 



of cast-iron or of case-hardened wrought-iron. The pillar 
is of steel, and may be rigid in the base block or carried 
in a rocking bracket. This rocking bracket allows the pillar 
to be fixed at any angle, and gives the tool a wider reach; 
but it usuall}^ lacks the adjusting screw by which the fixed pillar 



MEASURING AND MARKING-OUT TOOLS 105 



and scriber may be finally adjusted for very exact markings. 
This screw is seen in Fig. 51. 

The scriber is of cast-steel, with one straight and one 
curved point, which are hardened and tempered. It is 
carried in a needle clasp attached to the sleeve, and both are 
tightened by a single knurled nut. Scribing blocks are 
measured by the length of the pillar, 6 to 8 inches being the 
most convenient for school workshop use. When marking 
the ends of bars for centering, the work must be placed in 
the vee blocks, and the centre estimated by the eye. A 
mark is made, and the work rotated and marked in four 
positions, as shown in 
Fig. 178 (p. 192). A 
small square is thus 
obtained which fairly 
accurately fixes the 
centre of the bar for 
centre-punching . 

Vee Blocks. — Vee 

blocks (Fig. 52) are 
generally made of cast- 
iron, and are used for 
holding round bars 

whilst centering for turning, marking out keyways, marking 
centres for drilling, and also for holding circular work on the 
table of the drilling machine when drilling holes at right 
angles to the bar axis. They are usually made and sold in 
pairs. The most useful size for the handicraft - room is 
4 inches long, IJ inches high, and 1 inch thick, with a vee 
1 inch deep cut to an angle of 90 degrees. 




Fig. 52. 



CHAPTER XIII 

SMALL HAND TOOLS 

Mallets. — Mallets are more suitable than hammers for the 
working of soft or thin metals, such as tinplate^, copper, brass, 
zinc, aluminium, etc. The blow from a steel hammer is 




Fig. 53. 




fierce, and when not carefully used is apt to mark the materials, 
especially in such operations as flattening, folding, bending, 
or bossing. 

Flat-Faced Mallets. — Mallets for use in the handicraft-room 
were formerly made of boxwood, but the flat-faced mallet has 
now been superseded by the hide mallet. This mallet, which 
is made of pigskin, is superior to the boxwood type, as there 

106 



SMALL HAND TOOLS 



107 




Fig. 55. 



is no tendency to split, and, the material being of a softer 
nature, there is not the danger of marking. The most 
suitable size for handicraft purposes is 1^ inches diameter, 
with a 9-inch lancewood handle (see Fig. 53). 

Egg-Ended or Bossing Mallets. — These are usually turned 
by lathe, are made of boxwood, and fitted with cane handles. 
The smallest size, known as " 0,"^ having a maximum diameter 
of 2 inches, is most suitable for school purposes (see Fig. 64). 

Hammers. — Although the 
hammer is the oldest and 
most common tool in use, 
its actions are very little 
understood or studied. It 
is often given to a boy to 
use without either demon- 
stration or instruction, with 
the result that much valu- 
able work is either damaged 
or destroyed, and a large 
proportion of the energy 
expended in its use is lost. 
The blow must at all times 
be flat, and on no account 
must the edge of the " face " 
be allowed to come in con- 
tact with the work, as it is 
neither good for the work 
nor the tool. It should 

be worked from the wrist, with a firm grasp of the end of 
the handle; and if more power is required, it can be ob- 
tained b}^ changing the fulcrum from the wrist to the elbow 
or shoulder as required. 

Various shapes and sizes of hammers are made to suit 
various operations, but in metal-working the " ball-paned " 
engineer's pattern (Fig. 55) is most suitable. 




Fig. 56. 




Fig. 57. 



108 



METAL-WORK 




Fig. 58. 



The ball-pane is useful for bossing, riveting, scarfing, etc. 

Hammers with a straight pane running either parallel or at 
right angles to the long axis of the handle, as shown in 
Figs. 56 and 57, is more common in America than in this 
country. 

Hammers are specified by weight and pattern. For handi- 
craft purposes the most convenient weights are 12 ounces for 
bench work and 1 J pounds for forge work. 

Sledge - Hammers are made in 
three types — ^namely, double-faced 
(Fig. 58), straight-pane (Fig. 59), 
and cross-pane (Fig. 60). 

Fig. 58 is the commonest, and 
Fig. 60 the oldest. Sledges vary in 
weight from 2 to 14 pounds, those 
from 3J to 4 pounds being most suited 
to the strength of school students. 

The Repousse Hammer (Fig. 61) 
is used for light modelling work in 
brass, copper, or aluminium. It 
has a very wide face and small round 
pane. The handle is very slender in 
the neck, thus allowing the hammer 
to spring and so reduce the shock 
on the hand; and as the hammer- 
ing in repousse work is usually carried on for lengthy periods, 
it will be seen that this " springing "" of the handle is very 
important. The handle terminates in a thick oval-shaped 
portion, to allow comfort and command in the grasp. 

In tinplate working hammers of special shapes are necessary 
for the various operations, and include — 

The planishing hammer (Fig. 62), for flattening and working 
out dents. 

The square-edged hammer (Fig. 63), for working up sharp 
angles and corners. 




Fig. 59. 




Fig. 60. 



SMALL HAND TOOLS 



109 



The paning hammer (Fig. 64), for wiring and tucking the 
fold of material close around the wire. 




Fig. 61. 



The creasing hammer, for working creases, is similar to the 

paning hammer, except that the edge is round instead of flat. 

Hammers are always made from cast-steel, and to give 





Fig. 62. 



Fig. 63. 




Fig. 64. 



hardness, combined with elasticity, should be tempered in 
oil. Hickory and ash are the most suitable woods for hammer 
handles. 



110 



METAL-WORK 



Chisels. — There are four kinds of chisels commonly used 
in the metal handicraft-room, each forged from J-inch octag- 
onal cast-steel, 6 to 7 inches long, with a " draw-down "" of 
about 2 to 3 inches. 

The " flat "" chisel (Fig. 65) has a broad cutting edge, which 
should be parallel to the flats of the octagon. This edge is 
sometimes made straight, but by making it slightly round 
the tendency of the corners to " dig-in " is reduced, whilst it 
also enters the work more smoothly. The flat chisel is used 






ft 




Fig. 65. 



Fig. 66. 



Fig. 67. 



Fig. 68. 



for chipping broad surfaces, cutting out sheet metal, and 
cutting off bars and rods. 

The *' cross-cut " or " Cape "" chisel (Fig. 66) is shaped so that 
its cutting edge is slightly wider than the body. This will be 
found an advantage in cutting key ways, etc. The width of 
the metal behind the cutting edge is forged to about twice 
the width of the octagonal bar from which the tool is made, 
thus stiffening and supporting the edge. The width of the 
cutting edge varies from |^ to f inch, according to the re- 
quirements of the work. The principal use of this tool is 
the cutting of slots and key ways. In chipping broad surface 



SMALL HAND TOOLS 



111 



work, it will be found convenient to first cut a number of 
parallel grooves with this chisel, leaving a space between, 
which is slightly narrower than the width of the flat chisel. 
These parts are afterwards removed by the aid of the flat 
chisel. 

The " diamond-point '' chisel (Fig. 67) is forged down 
square. The edge is formed by a single bevel taken on the 
diagonal, thus presenting a diamond-shaped face. This chisel 
is used for cutting out and clearing square corners, cutting 
small vee grooves, and squaring drilled holes, slots, etc. 

The " half-round,"" ]$mnd-nose, or gouge chisel (Fig. 68) 
closely resembles the cross-cut in shape, but has one edge 
convex. The edge is formed by a single bevel. It is used 
principally for chipping concave flutings, such as oil channels, 
and for " drawing " a hole which has been drilled out of truth. 
The cutting angles, thickness of cutting edge, and temper of 
chisels, vary with the material to be worked. The following 
table shows the angle and temper for common metals : 



Metal. 


Angle. 


Temper. 


Cast-steel 
Cast-iron 

Mild-steel 

Brass . . 
Copper. . 
Zinc, lead, aluminium 


65° 
60° 
55° 
50° 
45° 
30° 


Very light straw. 
Light straw. 
Dark straw. 
Medium straw. 
Dark straw. 
Purple. 



The thickness may be taken as | inch for cast-steel, -^ inch 
for zinc, lead, and aluminium, and a proportionate thickness 
for the other metals in the order stated in the above table. 

The correct method of holding the chisel in chipping is 
shown in Fig. 69. After the first cut, the chipped edge always 
steadies the cutting edge of the tool, so the worker's hand 
should grasp as near the chisel head as possible. This keeps 
the tool quite steady, thus giving a better chipped surface, 
and tending to greater safety of the worker's hand. The 



112 



METAL-WORK 



correct position is to stand well away from the vice, giving 
the body a slight motion with the hammer blows. The 
hammer must be grasped at the extreme end of the handle, 
and allowed to swing well back, with a movement from the 
shoulder rather than from the elbow, at a rate of from thirty 
to forty blows per minute. The eyes must be kept on the 
work, and the chisel kept at a constant angle. This can 
only be done by keeping the tool close up to the work, and not 
allowing it to draw^ away at each blow. For cutting work 
other than chipping, the thickness and hardness of the metal 




EiG. 69. 

will determine whether the motion in swinging the hammer 
should come from the wrist, elbow, or shoulder, but in every 
case the extreme end of the handle must be grasped. 

Pliers. — Pliers are made of cast-steel and of many patterns. 
Those of the parallel-grip pattern will be found most convenient. 
The most common and useful in the handicraft-room are — 



1. Flat-nose (Fig. 70). 

2. Cutting (Fig. 71). 



3. Round-nose (Fig. 72), 

4. Stocking (Fig. 73). 



SMALL HAND TOOLS 



]13 




Pig. 70. 




Fig. 71. 




Fig. 72. 




Fig. 73. 



114 



METAL-WORK 



They are used for many different purposes, amongst which 
may be mentioned — 

1. Holding metal over a gas flame or fire for the purpose 
of annealing, tempering, etc. 

2. Holding together tinplate whilst soldering. 

3. Wire bending and cutting. 

4. Forming scrolls, etc., of ribbon iron. 



Fig. 74. 




Fig. 75. 



Fig. 76. 



Spanners.— Spanners are used for tightening and loosening 
nuts and set screws. As these vary in size, a complete set 



SMALL HAND TOOLS 



115 



varying from J to 1 inch should be included in the equipment 
of the handicraft-room. These can be obtained either single- 
ended, as in Fig. 74, or double-ended, as in Fig. 75. An 
adjustable spanner will also be found very useful. The type 
shown at Fig. 76 is perhaps the most useful. Spanners are 
made of cast-steel, case-hardened mild-steel, or malleable 
cast-iron, and, when of the two first materials, are usually 
shaped by the process known as " drop-forging. '^ In dealing 
with spanners, it must be noted that the size stamped upon 
the tool is the diameter of the bolt the nut of which the spanner 
is intended to fit. The British standard for nuts across the 
flats is one and a half times the diameter of the bolt plus 
J inch. Therefore a spanner stamped " J inch " would be one 
and a half times | inch plus J inch (= | inch) across the jaws. 

Saws. — Saws are used in metal- work for cutting sheet metal 
to required shapes, and bars and rods to required lengths. 
Fig. 77 shows a piercing saw. This saw is very useful in 




Fig. 77. 



dealing with decorative work in the softer metals, and also 
in light work with the harder metals. The type shown is 
capable of extension up to 6 inches, but the most useful 
size and make of blade is the " round back blue, "" 4 to 
5 inches long. 

The piercing saw carries the blade with the teeth pointing 
towards the handle, thus cutting on the downward stroke. 
Fig. 78 shows the correct method of holding the saw. 

Figs. 79 and 80 show the " hack " saw, which is much 



116 METAL-WORK 

heavier and stronger than the piercing saw, and is used for 
general work. 

The frame may be obtained for one size of blade only, or 
adjustable. When of the latter type, it will take blades of 





Fig. 78. 

three or four different lengths. The blades are made 8, 9, 
10, 11, and 12 inches long, in two sizes of teeth, " coarse " 
and " fine.'" The coarse blade has fourteen to sixteen teeth 
per inch, and is used for all ordinary work; whilst the fine 
blade has twenty-two to thirty teeth per inch, and is used 



SMALL HAND TOOLS 



117 



for such work as thin tubes and very thin sheet metal. All 
blades are J inch wide, and usually 0-025 inch thick, the teeth 



^i^J'^laa>fe:^M^DJBn^!^IOOERS^I^L!.S^Cgyfe^^ 




Fig. 79. 




Fig. 80. 




Fig. 81. 



being " set '" or " staggered "" so that the cut is just under 
Jg inch wide. The teeth are set to allow the blade to follow 
the teeth through the work without hindrance by friction 



118 METAL-WORK 

between the saw and the sides of the saw-kerf. Blades for the 
hack saw can be obtained either hardened right through, or 
with the teeth hardened and the " backs "" left soft. The former 
give good results in skilled hands, and last longer; whilst 
the latter are perhaps better suited to the frequent faulty 
handling by boys in the handicraft-room. The soft backs 
prevent easy breaking, although the teeth do not last so long. 
A 10-inch hack saw will be found most suitable in the handi- 
craft-room. 

Fig. 81 shows the correct handling of this tool, the right 
hand holding the handle with a grip similar to the file handle, 
and the left steadjdng the front of the frame with a very 
light grip, the thumb and two first fingers only being used. 
It is very essential that the tool be held correctly if true square 
cuts are to be made. The rate for using the saw is about 
thirty strokes per minute. 

Taps. — Screw threads are divided into two classes — in- 
ternal and external. Threads of either class above 1 inch 
in diameter are usually produced in the lathe ; but below this 
size the most satisfactory method of producing an internal 
thread is by " taps,'" and external by " stocks and dies.'^ 
Taps for general use are made in sets of three for each size 
— an " entry "" or " tapering " tap, an " intermediate "" or 
" second "" tap, and a " plug "' or " bottoming "' tap (Fig. 82). 

The first is tapered so that the small end is not larger than 
the tapping size of the hole, or the diameter between the top 
of the threads. If this tap were passed completely through 
the hole, a full thread would be cut. When the hole to be 
tapped is " blind,'' or does not go completely through the 
metal, this cannot be done, so it is followed by the inter- 
mediate tap, which is tapered only in the first few threads. 
As the first tap has not passed through, this taper is necessary 
to allow entry into the hole. This is succeeded by the bottom- 
ing or plug tap, which is parallel throughout its length, and 
cuts a full thread to the bottom of the hole. To give a good 
cutting edge, taps must be properly " backed off." 



SMALL HAND TOOLS 



119 



Small taps are sometimes made by filing four flats on the 
threaded portion; but, as the cutting angle is somewhere 
about 135 degrees, they are far from satisfactory. " Fluting " 
to form cutting angles is now almost universal, and gives an 
angle of about 90 degrees. The Whitworth Standard, which 
is in general use in Britain, and is shown in Fig. 83, provides 
three flutes; whilst four is common in America. The size 
of flute in British taps can be obtained by dividing the circular 




Fig. 82. 

section into a regular hexagon. Alternate portions are fluted 
out to form a semicircle, and the three remaining portions are 
threads. 

Taps are always made from cast-steel of very high quality 
and of uniform texture, and are hardened and tempered to a 
light straw colour. For " hardening " a tap, water is used 
in which common salt has been dissolved. After the tap has 
been heated to a uniform cherry red, the water is stirred 
round to form a small whirlpool, into which the tap is plunged 



120 



METAL-WORK 



perpendicularly, thread first. Taps hardened in this way 
seldom warp or bend out of shape in the process. The temper- 
ing process is then proceeded with as follows: Polish with 
emery-cloth until quite bright. Next heat to redness a short 
length of gas-barrel in the forge, and hold the tap inside until 
heated sufficiently to charge the bright metal uniformly to a 
deep straw colour, and then cool out by plunging into water. 

The neck and square 
shoulder must now be 
tempered to light blue by 
holding in a bunsen flame . 
In a first lesson on 
tapping, a student 
should not be given a 
tap smaller than f inch 
diameter, as with smaller 
sizes there is danger of 
breakage, owing to faulty 
handling and lack of 
knowledge of the shear- 
ing power of the material 
from which they are 
made. 




Fig. 



83, — Section of Whitwoeth Tap 
SHOWING Backing. 



The most common causes of breakage are — 

1. The application of unnecessary force. 

2. Unconscious bending by applying unequal force to the 
two handles of the wrench. 

When a broken tap cannot be extracted by pliers, it must 
be heated to draw the temper, and a hole drilled up the centre. 
This hole should be enlarged until the tap can be split across 
the flutes and the pieces removed. 

Fig. 84 shows the old type of wrench used for turning taps. 
It is usually fashioned of mild-steel, case-hardened round the 
hole, and is made to suit one set of taps only. With this 
tj^e a separate wrench is necessary for each set of taps. 
Adjustable wrenches capable of taking a wide range of tap 



SMALL HAND TOOLS 



121 



sizes are becoming popular. There are many types or pat- 
terns, one of which is shown at Fig. 85. When tapping 
wrought-iron, cast-iron, steel, or copper, oil should be used 
as a lubricant, but it is not necessary for brass or aluminium. 

It is of the utmost importance that 
holes for tapping should be of the 
correct size, for if they are too large a 
full thread will not be formed, and if 
too small it will be difficult to enter the 
taper tap, and there is great danger of 
the excessive work breaking the tap 
by shearing. The correct diameters of 
tapping holes are as follows : 



Diameter of 


Tapping 


Thread. 


Size of Hole 


i 


inch. 


3 


inch. 


3 




9 




T^ 




"5^4 




1 




3 




4 




TB^ 




5 




1 




TS- 




4 




« 




1 9 




¥ 




1ST 




r 




2 3 




TF 




"6"4 




JL 




1 3 




2 




"3^ 




y 




15 




T^ 




■^¥ 




5 




3 3 




g 




BT 




3 




6 




4 




¥ 




7 




4? 




8 




-WT 




1 




2 7 






•5-5- 






Screw Plates. — Small external screw 
threads of J inch diameter and under 
are generally cut by screw plates. 

A screw plate (Fig. 86) consists of a 
flat plate of the best cast-steel, the 
thickness of which is equal to the 
diameter of the largest screw. This 
plate is drilled with a number of holes 
and tapped, a series of from two to six fig. 84. 
holes being us^ed for each size of screw. 

For the smallest screws two or three holes are sufficient, but 
for the larger sizes six are used. The number for each size is 
distinguished by being joined together by chisel lines on the 




EiG. 85. 



122 



METAL-WORK 



plate. The holes are slightly opened out on the starting side 
of the plate, and are provided with cutting edges. These 
cutting edges are obtained by several methods, the two 
most common of which are shown at Figs. 87 and 88. 

Fig. 87 gives a sharp cutting angle and 
plenty of clearance for the cuttings, but the 
small amount of metal left at the actual cutting- 
point renders it liable to break when used for 
anything but the lightest work. 






Fig. 87. 



Fig. 88 does not give such a sharp cutting 
angle or such clearance for cuttings, but is 
stronger. 




Fig. 86. 



Fig. 88. 

Screw-plates usually act as much by pressure 
as by cutting. The screw-blank, on being 
screwed into the plate, has the groove between 
the threads partly formed by pressure, and the 
thread itself partly formed by the metal being pressed out of 
the hollows into the ridges. The screw thus produced is often 
larger in diameter and longer than the blank before thread- 
ing. The point of the blank must be filed slightly to a point 
to allow it to enter, and the plate kept quite square. 



SMALL HAND TOOLS 



123 



Oil is used as a lubricant when screwing iron, steel, copper, 
or aluminium, but is not required for brass. External threads 
from J to 1 inch are cut by stocks and dies, which act more by 
cutting than by pressure, thus diminish- 
ing the great expenditure of power 
which would be necessary in using a 
screw-plate. 

Stocks and Dies are made in various 
types, the most common being shown 
at Fig. 89. The dies are made in two 
halves, and fitted to the stock by 
vee-shaped grooves, the angle of which 
is usually 60 degrees. In these grooves 
the dies are free to move. The screwed 
portion of each die is about one-third 
of the circumference of the screw to be 
cut. A notch with a slight relief angle 
is cut out of the centre and at each 
end of the die, forming, when the 
pair are fixed for working, four screwed 
surfaces and eight cutting edges. When 
working the blank, four cutting edges 
act in each direction. Dies which 
have small screw surfaces cut quicker, 
and compress the screw less, than dies 
with large screw surfaces ; but the latter 
lead more truly, and maintain a better 
thread form. 

Stocks are made of mild-steel, with 
the recess for the dies and the point of 
adjusting screw case-hardened. The 
reason for case-hardening the recess is 
to prevent wear and avoid burring 

of the screw point. The dies are made of best cast-steel, 
hardened and tempered to a medium straw, after which 
they are cooled in oil to prevent brittleness. When using the 




Fig. 89. 



124 METAL-WORK 

stocks and dies, the end of the blank should be slightly 
chamfered. The dies are now placed on the top of the blank, 
and tightened just sufficiently to hold them in position (care 
being taken to see that they are square), and turned down 
to the required distance. The first screwing will trace the 
thread lightly on the blank. By screwing the dies back to 
the top of the blank, slightly tightening the adjusting screw, 
and repeating the operation a sufficient number of times, 
the full depth is cut. The dies must not be forced when cut- 
ting, or a bad screw will be produced. If the nut does not 
fit when the thread is full on the blank, the top of the thread 
must be filed off before taking another cut, otherwise a 
stripped or broken screw is sure to be the result. 

The lubrication of the various metals is the same as when 
using the screw-plate. Three pairs of dies are usually fitted 
to each stock. The following are common stock sets: 
8^^ Te^ 4 men; ^, y^-, g^ men; ^, g, ^ men; q^, yg^, ^ men; 2, §, 
f inch; f, f, 1 inch. Intermediate sizes are supplied in some 
sets, and can always be obtained if required. Screws above 
f inch and below | inch diameter are seldom used in the 
handicraft-room, those varying from i to J inch being most 
common. 



CHAPTER XIV 

SHEET METAL WORK, SOLDERINa, AND BRAZING 

The metals used in the handicraft-room for sheet metal 
working are copper, brass, and tinplate. 

Tinplate, which is used for all preliminary work in this 
branch of metal-working, is made from sheet steel coated 
with tin. In the manufacture of tinplate the best mild- 
steel sheet is employed. The surfaces of the plates are 
chemically cleaned by immersing in a bath of sulphuric acid 
and afterwards scouring with sand. After being thus pre- 
pared, they are plunged into melted tallow, which acts as a 
flux, and then into a bath of molten tin, where they remain 
for about three to five minutes. They are then withdrawn, 
allowed to drain and cool, then poHshed with bran. Before 
packing they are wiped over with oil. 

" Block tin " or " doubles," which is used for best work, 
is twice dipped into the molten tin. 

The tinning of copper is the same in principle, but usually 
much simpler in operation, as generally only one side requires 
tinning, and the material is either wholly or partly worked 
up previously. All copper articles which are to come into 
contact with food should be coated with tin, to protect the 
copper from the action of inorganic acids. Before tinning 
copper, the metal should be cleaned with dilute nitric acid 
and scoured with silver sand, to produce a clean metallic 
surface. The metal is then washed over with zinc chloride, 
sprinkled with finely crushed sal-ammoniac, and placed over 
a gas-stove, with a small piece of tin or fine solder resting on 
the surface. In a short time the tin will fuse, and the plate 

125 



126 



METAL-WORK 



should be gently moved until the liquid has covered the whole 
surface. Any surplus tin must be shaken off. If there be 
any spots to which the tin will not adhere, they should be 
rubbed with a block of sal-ammoniac. Any ridge which tends 
to form on the edges can be removed by gently and quickly 
wiping with a piece of moleskin cloth. 

Tools and Appliances.^ — Metal-plate working tools are very 
numerous, and chief amongst them are the various stakes. 
These tools are for bending and folding, and when in use fit 
into holes in the bench or are held in the vice. They are 
usually made of mild-steel faced with hard cast-steel. 

The Tinman's Anvil (Fig. 90) has a highly polished flat 
face. It is used for planishing and straightening plates, and the 
curved edge is useful in throwing edges or beads of large radii. 





Fig. 90. 



Fig. 91. 



The Tinman's Horse (Fig. 91) is for holding the small 
" horse heads,'' used for bossing out or working hollow work. 

The Hatchet Stake (Fig. 92) varies from 4 to 20 inches on 
the edge, but one about 12 inches will be found to meet all 
the requirements of the handicraft-room. Its principal use 
is the bending of small edges and acute angles. 

Creasing Iron (Fig. 93) is used for folding a wired edge, 
the wired portion being placed in a suitable crease and 



SHEET METAL WORK 



127 



lightly tapped with a mallet. This tool is also useful for 
working a bead on a flat surface, when a creasing hammer 
is used. 



s^ 



Fig. 92. 




Fig. 93. 




Fig. 95. 



Fig. 96. 



Bich-Iron, Funnel, and Extinguisher Stakes (Figs. 94, 95, 
and 96) are used for working cylindrical and conical objects. 



128 



METAL-WORK 



Half-Moon Stake (Fig. 97) is useful when wiring circular 
edges and for closing acute angle joints. 





Fig. 97. 



Fig. 98. 



Round-Bottom Stake (Fig. 98) is used for riveting and for 
straightening work after the edge has been thrown up on 
other stakes. 

Folding Bars, as at Fig. 99, are the most suitable tools for 
straight bends and folds. 



I 



Q^D CXJ^Z? oJ^'d 




Fig. 99. — Folders with Holes for punching Tinplate. 

" Shears "or'' Snips " (Fig. 100) are used for cutting sheet 
metal. The Scotch shears shown (Fig. 101) may be used for 
cutting thick copper and brass, but for tinplate the shears or 
snips will be found more suitable. 



SHEET METAL WORK 



129 



For trimming large work, for all straight or convex cuts 
in small models, and for intricate cuts other than concave. 




Fig. 100. 



the straight snips will be found useful; while for concave 
cuts the curved or bent sni]3s shown at Eig. 102 are indis- 




FiG. 101. 



Fig. 102. 



pensable. The angle of the cutting edge for shears and snips 
is 87 degrees. 

Flattening Sheets. — Bends can be straightened out by lajdng 
the plate on a flat surface and striking lightly with a mallet. 

Buckles in plates are caused by what is termed "loose 
metal '' in the centre, and can be removed by stretching the 
edges. This stretching is done by lightly hammering the 
edges of the sheet. 

Wiring. — The method of folding the edges to receive wire 
varies with the shape of the edge. The simplest form of 
wiring is a straight edge, when the fold can be made by bending 
the plate in the folding bars or over the hatchet stake. The 
amount of metal to be folded over is slightly more than twice 
the diameter of the wire. V/hen the fold is prepared, the 
wire must be held closely under it, and the metal slowly worked 
over with a mallet or small hammer. It must be remembered 
that, if buckles in folding are to be prevented, the fold must 
be worked over by degrees. The edges are finally " tucked " 
in with a small straight-paned hammer, and the whole edge 



130 METAL-WORK 

straightened out on the creasing iron, as previously mentioned. 
When wiling sharp angles, as in the tidy-box in the scheme 
of work on p. 256, the metal should be snipped tlu-ough for 
the distance of the fold at the position of the two right-angled 
corners. The wii'ing is then done in the straight, followed by 
the bending for the box, thus leaving the wiring exposed at the 
corners. 

Cylindrical models which have to carry a wired edge are 
always wired in the flat, and afterwards bent into circular form. 
When wiring shapes which are circular in the flat, the edge 
should be thrown up on the half -moon stake. 

A good deal of the bending and shaping in tinplate-work 
can be done by pressure of the fingers, together with just a 
little hammering to obtain the sharp edges. In cylindrical 
or conical work, the form can be obtained to a large extent 
by bending and rubbing the material with the hands over 
the bick iron or funnel stakes. This reduces the danger of 
marking, and leaves, especially in flat surfaces, a better face 
on the plate. Any hammering done must be carefully per- 
formed, so that the surface is not damaged. 

When forming a joint, it will be found convenient to hammer 
down the fold u]3on a piece of plate equal to the metal being 
worked. If this is done in the folded seam, for instance, it 
allows the two j)ieces forming the joint to go together in a 
comparatively finished state, and insures a good straight edge. 
A little light hammermg after the pieces are together then 
forms a tight, well-finished joint. 

The joints (sometimes called " seams "") used in metal- 
plate are shown at Fig. 103. 

The whole of these joints, except L and M, are soldering 
joints, and are soldered on both sides after the joint is thr own- 
up. L and M are brazing joints. Riveted joints are seldom 
used in sheet metal working, but when they are employed the 
lap is always three times the diameter of the rivet. The 
process of uniting or joining metals by the application of 
fusible alloys of lead and tin, which fuse below red heat, is 



SHEET METAL WORK 



131 



called " soft soldering/' When the uniting alloy is composed 
of copper and zinc, which fuses above red heat, the process is 
termed " brazing "" or " hard soldering/' 



A. Lap Seam. 



B. Counter- Sunk 
Lap Seam. 



Q Folded Seam. 



D. Grooved Seami 



E. Doubled Folded 
Seam. 



F. Zinc Joint. 



G. 



Circular 
Lap Seam. 



Circular 
Over-Folded Seam. 



H 



Circular 
Folded Seam. 




Box 
Grooved Seam. 



M. 



Housed Joint. Dovetail Joint. 

Fi&. 103. — Sheet Metal Joints. 

A. Lap Seam. — 'A convenient joint, but not very strong or reliable. 

B. Counter-Sunk Lap Seam. — -Similar to A, but with one edge bent down 

so that the joint may present an unbroken surface. 
G. Folded Seam. — A strong reliable joint which is very suitable for articles 
to hold liquids. 

D. Grooved Seam. — Similar to G, but with one plate counter-sunk, so that 

the joint may present an unbroken surface. 

E. Double Folded Seam. — A strong joint used for thick plate. Presents an 

unbroken surface. 

F. Zinc Joint. — Used for jointing large zinc plates. It allows of expansion 

and contraction. 

G. Circular Lap Seam. — Used for the bottoms of cylindrical objects. Such 

bottoms are said to be " snuffed on." 
H. Circular Folded Seam. — Also used for bottoms of cylindrical objects. 

These bottoms are said to be " panned down." 
J. Circular Over-Folded Seam. — -Used for purposes similar to G and //. This 

is a strong, useful joint, and quite water-tight. These are termed 

" knocked-up bottoms." 
K. Box Grooved Seam. — -Used for joining plates at corners in square work. 

Very strong and reliable. 
L. Housed Joint. — Used for joining thin plates. The pieces are forked 

over each other. 
M. Dovetail Joint. — Used for thick plates 



132 METAL-WORK 

" Brazing "'' with an alloy of copper and silver is termed 
" silver soldering/' 

Soft Soldering. — Soft soldeis are usually applied with a 
heated copj^er bit, or bolt (often misnamed the soldering 
"iron""), which consists of a copper working end called the 
" bit/' riveted to a steel bar which is fitted into a wooden 
handle. Copper is always used for this tool, because of its 
property of retaining heat and its affinity for solder, by which 
it collects and holds the alloy. 

Bits vary in shape and size according to the requirements 
of the work. Fig. 104 shows the ordinary square-pointed 




Fig. 104. 

tool. The size most suitable for the handicraft-room has a 
copper bit 3J inches long, weighing 8 ounces, and a total 
length over all of not more than 12 inches. The total length 
can be easily adjusted, if too long, by removing the handle, 
cutting off part of the steel shank, and refixing. The copper, 
which may be round or square in section, must not exceed 
8 ounces in weight. Fig. 105 shows the " hatchet " copper 




Fig. 105. 

bit, which is used for soldermg the bottoms of cylindrical 
vessels, such as saucepans, kettles, etc. Soldering bits are 
ordered by stating the weight of the copper end required. 

Stoves. — Gas-heated stoves are most convenient in the 
handicraft-room for heating soldering bits, having the ad- 



SOLDERING AND BRAZING 



133 




Fig. 106. 




Fro. 107. 




Fig. 108. 



134 METAL-WORK 

vantage of safety, requiring little attention, and being quickly 
made ready for use. Coal or coke stoves, besides being more 
difficult to prepare, are also more liable to burn the " tinning " 
off the copper. Suitable stoves are shown at Figs. 106 and 
107. The automatic stove shown at Fig. 108 has an arrange- 
ment whereby the withdrawing of the bit lowers the gas, 
thus effecting a saving of 50 to 60 per cent, in gas consump- 
tion. Fig. 106 shows a stove the top of which is hinged, 
and can be opened or used for heating ladles, tinning, or 
lacquering. 

Tinning the Bit. — Before the bit can be used in soldering, 
the point of the copper must be coated with solder, or tinned, 
otherwise the solder will not adhere to it. To carry out 
this preparation, heat the bit to a dull red, grip in a vice, and 
file the faces of the shaped point quite bright. Dip the point 
quickly into zinc chloride, and rub it on a piece of sal- 
ammoniac, at the same time holding a bar of solder against 
the bit to run a little into the sal-ammoniac. Turn and rub 
the bit. The solder will then coat the faces of the copper. 

Fluxes. — Metals to be soldered together must be chemically 
clean, otherwise the solder will not adhere. All oxides must 
therefore be removed. This is effected by applying a " flux.'^ 
Different metals requke different fluxes, and in every case, 
not only must the oxides be removed, but their formation 
during the soldering must be prevented. The most common 
flux is " zinc chloride,'' or " killed spirits of salts.'' It is pre- 
pared by dissolving zinc in hydrochloric acid (known as " spirits 
of salts"). Zinc must be added to the acid until all trace of 
ebullition ceases, when the acid is said to be " killed." If 
any free acid remains, a black stain will appear in tinplate 
after soldering. A piece of common washing soda or sal- 
ammoniac is sometimes added to the solution to make sure 
that any remaining free acid shall be neutralized. For 
ordinary soldering purposes a solution of equal parts of zinc 
chloride and water will be found sufficiently strong. 



SOLDERING AND BRAZING 



135 



A paste form of flux, which is not so liable to cause rust as 
the solution, is made by boiling the liquid zinc chloride until 
all fluid is evaporated, leaving the solid crystals. These are 
ground together with an equal bulk of vaseline. 

The following table gives the soft soldering fluxes with the 
metals for which they are most suited : 



Fhix. 


Metal. 


Remarl:s. 


Zinc chloride with 


Tinplate, iron, steel, 


Very suitable for all ordi- 


equal quantity of 


brass, copper 


nary work, but must be 


water 




washed off after the 
joint is completed, or 
will cause rusting. 


Sal-ammoniac 


Copper 


Gives good results when 
tinning copper articles. 


Hydrochloric acid 


Zinc 


Is the only satisfactory 


with 90 -pev cent. 




flux for zinc soldering. 


water 






Tallow, Gallipoli oil, 


Lead, pewter, white 


Suitable for all metals and 


Venice turpentine 


metals 


alloys with low melting- 
points, such as " compo " 


Resin 


All metals 


pipes. 
Not a true flux, as it does 
not remove existing ox- 
ides. It should only be 
used when the metals 
can be scraped or filed 
bright before soldering. 
Prevents the formation 
of oxides during the 
operation. Has the im- 
portant advantage that 
it does not induce subse- 
quent corrosion. Much 
used in electrical work, 
particularly for wire 
jointing. 



Soft Solders. — Soft solders are composed of tin and lead in 
varying proportions. The following table gives particulars 
of the various soft solders and their approximate melting- 
points : 



136 



METAL-WORK 





Composition. 






Name. 




Melting- 
Points. 


Remarks. 








lead. 


Tin. 












°F. 




Plumber's coarse 
,, fine 


3 

2 


1 
1 


482 
440 


For joints in lead pipes. 
Strong, used bv gasfitters. 


Tinman's coarse 
,, fine 


1 
1 


1 
2 


320 
300 


Used for ordinary tin- 
plate work. 
Flows well. Used for best 


Pcwterer's 


1 1 

3 Bismuth 


240 


tinplate work. 
Very fusible. Used for 
soldering pewter. 



Process of Soldering. — ^A'\Tiatever form of heat is used for 
warming the copper bit, care must be taken to avoid the 
common mistake of only heating the point of the bit. The 
body should be heated, and the pomt kept out of the direct 
flame. Heated in this manner, the tool will keep hot longer 
and the point will not become rough or burnt. 

To judge the temperature, hold the bit about 6 inches 
from the side of the face, and when a perceptible heat is felt 
the tool is warm enough. When judged to be hot enough, 
dip sharply in zinc chloride to remove any oxides, and pick 
up a little solder with the bit and appty to the work, which 
in all cases has been previously wiped over with a suitable 
flux. The solder can be kejot ready for immediate use upon 
a piece of tinplate. The bit should be moved slowly over 
the joint to allow the heat to permeate the metal, and not 
rubbed backwards and forwards, as this is sure to make a 
rough joint. The appearance of the joint is an excellent 
guide to its soundness. It should be smooth and shining. 
If rough or of a sanded appearance, the bit was overheated 
or applied too quickly; and if the solder lies in lumps, there 
was insufficient heat. 

Sweating. — This term is applied to the method of coating 
the faces of two pieces of metal with solder, then placing them 
together and applpng heat until they unite. Very small or 



^SOLDERING AND BRAZING 137 

very large pieces of metal which could not be joined by 
the use of the bit can be united by this method. When 
several joints are close together, it is usual to place a wet 
cloth over each as it is soldered, to prevent the heat applied 
in subsequent jointing attacking the finished work. 

Aluminium cannot be soldered with the ordinary alloys of 
lead and tin, but in 1885 M. Christoffe, a Parisian goldsmith, 
discovered that x^ure tin or zinc would unite aluminium. In 
practice, however, neither is entirelj^ satisfactory, as the tin 
forms an alloy with the aluminium and the joint soon parts, 
while the zinc discolours very badly and quickly becomes brittle. 

Brazing, or Hard Soldering. — Brazing differs from soft 
soldermg in the fact that the uniting alloj^s have a higher 
meltmg-point, only fusing above red heat, and consequently 
cannot be applied with the copper bit. A forge or foot blow- 
pipe must be used to make the spelter (hard solder) flow into 
the joint. Brazing is useful where greater strength is required 
than can be obtained by ordinary soldermg, and where the 
article has to withstand a temperature higher than the melt- 
ing-point of soft solder. 

Heat. — The usual source of heat for brazmg is the gas 
blow^Dil^e, which is fitted to a brazier or hearth, underneath 
which are the bellows suppljmig the air. Fig. 110 shows the 
comx^lete brazier or brazing hearth. The hearth is filled 
with small asbestos cubes, about 1-inch sides, or with coke 
breeze, which, when packed around the joint to be brazed, 
concentrate the heat. In brazing moulds or beads around the 
outside of hollow objects, such as vases, etc., the inside of the 
work must also be filled with asbestos or coke. The blowpipe 
should be fitted with two valves, two types of which are shown 
at Figs. 110 and 111, to regulate the supply of air and gas. 

Flux. — Borax is the flux used for all metals when brazing. 
Its action is perfect, as when heated, it quickly combines 
with any oxides on the work, and fuses to a glassy paste, 
which protects the metal from any fm^ther action. Borax 



138 



METAL-WORK 



is composed of sodium, borum, oxygen, and water. It is 
found in Tibet, Tuscany, and North America, and large 




Fig. 109. — Brazing Heaeth 




FiQ. 110.— Blowpipe (Valve Each Side). 




Fig. 111. — 'Blowpipe with Valves together. 



quantities are manufactured chemically by combining the 
various elements of which it is composed. 



SOLDERING AND BRAZING 139 

Spelter. — The fusible alloys used for brazing are termed 
" spelters/" and are usually alloys of copper and zinc (brass). 
The temperature of the melting-point and the strength of the 
spelter are proportionate to the percentage of copper it con- 
tains, but the common proportions are 1 of copper to 1 of 
zinc. A spelter for brazing brass must contain a much 
greater percentage of zinc than the brass which is to be joined, 
so that the spelter will fuse without danger of melting the 
joint. Spelter can be obtained in a granulated powder or 
in sticks and wire, the suitabilitj^ of each depending upon the 
work in hand. 

Method of Brazing. — The flux must first be prej)ared. If 
wire is to be used for spelter, the borax must be powdered and 
formed into a thick paste by the addition of water, and a 
little spread along the joint. The heat is first applied gently, 
so that the flux is not displaced, and gradually increased 
until the joint is a dull red. Then take a stick of spelter, and, 
after dipping in borax, rub it along the joint until sufficient 
melts off. 

If granulated spelter is to be used, mix it with twice its 
bulk of borax, and form into a thin paste with water. Apply 
sufficient of the mixture to the joint, and heat as previously 
described until the spelter fuses. This latter process will be 
found most convenient in brazing the joints of cylindrical 
objects, where the closed form of the work hinders the appli- 
cation of the stick spelter. As the spelter fuses and becomes 
liquid, a gentle tapping of the work will assist it to flow evenly 
into and through the joint. After the joint has been flushed 
off, the work should be taken from the hearth and allowed to 
cool slowly. 

Silver Soldering. — Silver soldering is a process identical 
with brazing, except that the solder used has a much lower 
melting-point. The usual composition of this solder is 5 parts 
copper, 3 parts zinc, and 2 parts silver. Its low fusing tem- 
perature makes it a suitable spelter for uniting brass. 



CHAPTER XV 

FORGE WOEK 

Forging may be defined as the operation of shaping or join- 
ing of steel and wr ought-iron by the aid of heat. Technically 
the term " smithing " is applied to the making of small objects, 
and " forging "" to large work, but the product in both cases 
is known as " a forging/^ 

Forges. — For use in the handicraft-room, the forge, or, as 
it is sometimes termed, " smith's hearth,"" should be small and 
compact, the hearth being about 2 feet square. 




Casting 
Z' Fireclay 




Fig. 112. — Wet Tuyere. 



Fig. 113.— Dry Tuyere. 



Forges are broadly divided into two classes : (1) wet- 
tuyerecl, (2) dry-tuyerecl — " tuyere " being the name applied 
to the nozzle through which the blast enters the fire. 

The wet tuyere (Fig. 112) is made so that the nozzle is 
surrounded by a water-jacket, and has the advantage of not 

140 



FORGE WORK 



141 



being affected, to any great extent, by the heat of the fire. 
It thus gives very little trouble, and requires little or no 
attention beyond keeping the supply- tank filled with water. 
It is, however, more expensive in first cost. 

The dry tuyere (Fig. 113) is either built up of sheet-iron 
plates or cast-iron. The metal is protected from the heat 




Fig. 114. 



by a lining of fireclay, which has to be periodically examined 
and repaired, or totally renewed (when necessary). Under 
normal conditions, renewal is only necessary after about four 
months' use. The dry tuyere is 50 per cent, cheaper than 
the wet type, but the renewing of the fireclay is a continual 
small expense. 



142 METAL-WORK 

The air-blast in all modern forges is supplied by means 
of a mechanical fan which gives a draught which is constant 
and of even pressure. This is much superior to the older 
form of bellows, which drives the air into the fire inter- 
mittently or in puffs. Even the best form of bellows blower 
— the double type — ^while it produces a fairly constant draught, 
gives very uneven pressures, and is much inferior to the 
fan blower. Fig. 114 shows a complete modern forge with 
mechanical fan for air, which is quite suitable for the handi- 
craft-room. As the air comes into the fire in most forges 
through the bottom, there should be some means of opening 
the blast-pipe to extract any cinders which happen to pass 
into it. The most satisfactory fuel is hard coke breeze broken 
into pieces equal in size to a hazelnut, or, if coal is burnt, it 
should be soft, of even structure throughout, broken small 
and wetted, so as to aid the formation of coke. The fresh 
coal is banked round the outside of the hearth, and as it cokes 
is drawn into the fire. 

Anvil. — The anvil (Fig. 115) may be termed the principal 
tool or appliance used for forging. It is made of wrought- 



FiG. 115. 

iron or mild-steel, with a working face of cast-steel welded on, 
and is measured and specified by the breadth of the face. It 
consists of three working parts : 

1. The " beak," or conical portion, which is used for curved 
work, such as rings, hooks, etc. 

2. The " block,'' or small flat face adjoining the beak, wh ich 
is used for cutting upon to save the working face. 



FORGE WORK 



143 



3. The large working face, or " anvil face/' which is slightly 
rounded across its breadth to insure a solid blow being de- 
livered to the work. 

The square or " hardie " hole is to receive the shanks of 
swages or hardies. 

The anvil may be mounted on a cast-iron anvil-stand, as 
shown at Fig. 116, or upon a block of wood. The latter 




Fig. 116. 



method is better, as it is less noisy and gives a springiness to 
the blow. The most suitable size for the handicraft-room is 
a 4-inch face and a weight of about 100 pounds. In working, 
the beak should point towards the worker's left. 




Fig. 117. — Swage Block. 

The ^^ swage block" and stand (Fig. 117) are made of cast- 
iron. The block can be set up in any position required, and 



144 



METAL-WORK 



the edge grooves are used to finish work to various shapes 
whilst the holes are for heading or bending. 

The hot set (Fig. 118) is used for cutting off red-hot metal. 





Fig. 118. — Hot Set. 



Fig. 119.— Cold Set. 



The cold set (Fig. 119) is used for cutting off cold metal. It 
will be noticed that this tool is much thicker than the " hot 
set."' Care must be taken not to use the cold set to cut hot 
metal, as the heat will draw the temper and leave the edge 
too soft for cold-metal cutting. 

The edge of the chisels must never be allowed to cut com- 
pletely through the metal and come into contact with the 
working face of the anvil. It will be found sufficient to cut 
partly through from one or both faces, when the metal can 
be broken. If thin material is to be cut, it must either be 
cut on the " block " of the anvil, or a strip of mild-steel, about 
4 inches wide, and long enough to cross the anvil face and 
A turn down 1 inch on each side, can be kept for 
\ placing on the working face as a cutting pad. 
The work must be quite flat before attempting to 
cut it. 

The ''anvil cutter" or '' hardie" (Fig. 120) is 
~ also used for cutting off, and is fixed in the 

* " hardie-hole.^' 
To2^ and bottom fullers (Fig. 121) are used for working 






Fig. 121. 



hollows, forming grooves, finishmg up corners, etc. The top 
fuller is supplied with a handle, and is used if a single hollow 



FORGE WORK 



145 



is required. The bottom fuller fits into the har die-hole, and 
is chiefly used in conjunction with the top fuller. 





Fig. 122. 



Top and bottom rounding swages (Fig. 122) are used for 
finishing and smoothing drawn-down round bars. 

The flatter (Fig. 123) is used for finishing flat surfaces. Work 




Fig. 123. 



finished with a flatter is always much smoother than that 
left from the hammer. 

Round and square punches (Fig. 124) are used to punch 
round or square holes. Holes obtained by punching through 




Fig. 124. 

red-hot metal have the advantage of not decreasing the sec- 
tional area of the metal. The bar swells out at the sides, and 

10 



146 



metal-work: 



leaves the sectional area full, so that the tensile strength is 
not diminished. 

Tongs are of various shapes to suit the different bars or 
plates. F:g. 125 shows the " rght angle " close tongs 




Fig. 125. 



Fig. 126. 



which are used for holding rings, large plates, and hollow 
work. Fig. 126 shows the fiat open-mouth tongs which are 
suitable for holding rectangular bars of a thickness not ex- 
ceeding the distance between the jaws when parallel. Fig. 




Fig. 127. 



127 shows the fiat close-mouth tongs used for holding thin 
plates or sheets. 

The pick-up tongs (Fig. 128), as their name impHes, are used 



Fig. 128. 



for picking up rivets, small round bars, etc., and also for 
holding metals for tempering. These tongs are very useful 
in the handicraft-room. 



FORGE WORK 



147 



The hollow bit tongs (Fig. 129) are used for grasping round, 
square, hexagonal, or octagonal bars. 



Fig. 129. 



Bolt tongs (Fig. 130) are for holding bolts, rivets, etc., the 
head being cleared by the " spring "' in the jaws. 





Fig. 130. 



The " reins,"' or handles, for forge tools in the handicraft- 
room should not be more than f inch diameter. 

Forge Work. — Forging can be classified into four primary 
and five secondary operations. 



Primary Operations. 

1. Bending, as in rings, links, hooks, etc. 

2. Drawing-down, as square and round points, chisel-ends, 
etc. 

3. Jumping-up, or upsetting, as bolt-heads, rivet-heads, 
cramp-ends, etc. 

4. Welding, as in chain-links, bolt-heads, etc. 



148 METAL-WORK 

Secondary Operations, 

1. Punching square, round, or rectangular holes. 

2. Cutting. Parting off a bar into various lengths or 
removing surplus material. 

3. Annealing. Softening hard metals, such as cast-steel. 

4. Hardening and tempering. Cutting tools and springs. 

5. Case-hardening. Obtaining a hard skin on soft steel or 
wr ought-iron. 

The objects which can be made by forging are of endless 
shape, size, and degree of hardness, but all resolve themselves 
into a recurrence or combination of the primary or secondary 
operations stated, the former being most frequent. 

Heats. — Wrought-iron and mild-steel will sustain any 
degree of heat up to their meltmg-pomts without injury; 
but cast-steel must be heated with great care. If it be heated 
above blood-red, it loses its carbon, crumbles under the 
hammer, and will not harden. Steel which has thus been 
overheated is said to be " burnt.'' 

The four chief degrees of heat which can be readily distin- 
guished when forging are — 

1. Low red, or blood heat. The metal just shows red in 
dayhght. This heat is suitable for working and hardening 
cast-steel. 

2. Bright red, or cherry heat. The metal shows full red 
with grey scales. This heat is suitable for bending wrought- 
iron or mild-steel. 

3. White heat. The metal shows quite white. This heat 
is suitable for " drawing - down '' wrought-iron or mild- 
steel. 

4. Welding heat. When the metal is just melting, and 
is shown by white-blue sparks flying from the fire and 
bursting. 

Bending. — Bending may be divided into two classes — angles 
and curves. Angles are more difficult to forge than curves. 



FORGE WORK 149 

from the fact that the metal becomes thin at the corner in the 
act of forming the sharp external angle. This operation is 
best performed with the metal at a high heat, as in this state 
a much sharper bend is obtained. If a right-angled corner is 
required, the metal must be kept at an angle of not less than 
100 degrees until the corner is forged. It is afterwards finished 
to the required 90 degrees. In curved bends, such as the 
poker-handle. Model 19 in the scheme shown, the bend where 
the ring joins the bar, or root bend, must be forged first. Then 
draw the ring round the beak of the anvil. In ring or curve 
bending the metal must never be struck immediately over the 
anvil, but just clear. This insures a bend without the danger 
of thinning rectangular, or of flattening round, material. 
When calculating the amount of metal necessary for bends, 
the centre line on the edge is measured, and in rings the mean 
diameter multiplied by tt (3*1416). 

Drawing-down. — When drawing -down wrought - iron, the 
metal should be worked at a good white heat, otherwise it is 
sure to split. Mild-steel, while less liable to split, is also best 
worked at a full red heat. In drawing-down a point, it is best 
to form a short, sharp pyramid first, and afterwards draw down 
to the required length. When forming a round point, first 
proceed as in a square, and when almost to the required size 
work off the corners until the cone is complete. If the bar is 
drawn out round, the point is always hollow, and frequently 
splits. This fault is termed " piping."" 

Jumping-up. — Jumping-up may be done by holding the 
bar across the anvil and striking the end with a hammer, or 
by holding the bar with both hands and " bouncing "' it upon 
the anvil face. These methods are usually employed when 
the amount of metal is long enough to allow it to be held in 
the hands. With smaller pieces which require holding with 
tongs, the work should be stood on end on the anvil and struck 
on the upper end with a hammer. The work must be kept 
upright, and if after a few blows it bends, it must be straight- 



150 METAL-WORK 

ened before proceeding farther. When jumping-up, the metaf 
must be kept at a good, even red heat, as if one part is hotter 
than another the metal will thicken most at the hottest part. 
If only a certain portion, is to be jumped, the parts which do 
not require thickening should be cooled in water to localize the 
heat. 

' Welding. — Welding is a most valuable property of wrought- 
iron and mild-steel. As most welding troubles arise through 
inattention to the fire, great care must be taken to have it 
clean and bright. During working the impurities m the fuel 
collect, and form a slag called " clinker. "" If allowed to collect 
to any extent, this clinker sticks to the metal, and when ham- 
mered into the joint seriously weakens it, and in manj^ cases 
totally prevents welding. 

Another common trouble in welding is the formation of 
oxides on the heated metal in the passage from the fire to the 
anvil. To prevent this formation, a flux — usually sand and 
borax — should be applied to the metal when approaching the 
correct heat. The flux flows at a lower temperature than 
welding heat, and, besides dissolving the oxides already 
existing, prevents their further formation. By the use of the 
flux a weld is possible at a lower temperature than without it. 
The preparation of the joint for welding is important. The 
ends are first prepared by jumping-up, to allow for the slight 
loss in diameter which always occurs in welding. This loss 
is chiefly due to the hammering required and the soft state 
of the metal at the moment. 

The material should also be scarfed — that is, formed in the 
fashion shown at Fig. 131. The scarf is left round rather than 
square or hollow, and roughened by a few blows with the 
hammer edge. The bars are now placed in the jDxepared fire 
and slowly heated, to insure an even heat right through the 
material. When welding heat is attained, blue- white sparks 
are emitted from the fire and from the metal. 

The bars must be quickly removed from the fire to the 
anvil, and after a slight jerk, to rid them of any foreign matter. 



FORGE WORK 



151 



laid together and hammered all round. The anvil face must 
be clean and all tools required placed in readiness, and in 
removing the bars from the fire care must be taken not to 
draw them through the fuel. 





sX:=i 



Fig. 131.— Scarf Welding. 
A, Overlap; B, flush; A, B, butt; G, round or square bars. 

Burning of the metal, due to carrying the heat too far, is a 
very common fault in welding. If a successful weld is not 
obtained, the metal should be cut and the process recommenced, 
as reheating is seldom, if ever, satisfactory. The amount of 
upsetting and scarfing is chiefly determined by experience. 




n 




STplit Welding [Round Metal). 



Split Welding {Thin Metal). 



Fig. 132. 



In welding thin iron or steel the " split weld '' is used (see 
Fig. 132). The two pieces when partly heated are placed 
together and the splits closed down, then raised to welding 
heat and worked together, 



152 



METAL-WORK 



For right-angled welds, the materials are prepared as at 
Fig. 133 for rectangular sections, and Fig. 134 for circular. 




Fig. 133. 



Fig. 134. 



The difficulties attending the welding of cast-steel put it 
outside the range of the handicraft-room, although the process 
may be described. Special flux, generally with prepared 
borax as a base, is used, and the correct heat is a bright yellow, 
which can onty be learned by experience. If the metal is 
heated until sparks are emitted it is quite useless. Even the 
most experienced workman can seldom make a satisfactory 
weld with two pieces of high carbon tool steel. 

Punching. — Holes of any particular shape may be obtained 
by punching. The process is carried out with shaped punches, 
while the metal is red-hot, by working through from both sides 
rather than from one side only, the punching on the second 
side being done over the round or square hole in the anvil. 
If these holes are too small, a suitable hole in the swage block 
is used. As has been already noted, holes formed in this 
manner have a great advantage over drilled holes, as there is 
no loss of material and consequent weakening of the bar. 



FORGE WORK 153 

Cutting. — Cutting in forge work is done with the setts^ hot 
and cold, as required, or by holding the bar on the hardie and 
striking with the hand-hammer. 

Annealing. — " Annealing "" is the term applied to the process 
of rendering metals less brittle. Iron and steel may be an- 
nealed by heating to redness, covering with cinders, and allow- 
ing to cool slowly. High-grade cast-steel if treated by this 
method loses some of its carbon, and consequently deterio- 
rates in quality. This class of steel is better treated by burying 
in lime, charcoal, cast-iron borings, or sawdust, after heating, 
which prevents loss of carbon. Another method of treating 
cast-steel, which gives excellent results, is to place the steel 
to be annealed in a cast-iron box closely packed with charcoal 
dust, then heat both box and contents to redness, and allow 
to cool slowly. Steel treated in this manner is clean and soft, 
and there is no loss of quality. 

Copper and brass are annealed by heating to redness and 
cooling by immersion in water. Zinc, lead, tin, and aluminium, 
can be annealed sufficiently to prevent cracking while working 
by heating in boiling water for a few minutes, and then cooling 
in the air. 

Hardening and Tempering. — Cast-steel is hardened by 
heating to redness, and cooling suddenly by immersing in 
water or other cooling medium. The hardness depends 
chiefly upon the speed of cooling from a high temperature. 
If cooled very quickly it becomes very hard, and if cooled slowly, 
as in annealing, it softens. The grade of hardness can therefore 
be gauged by the speed of cooling. The correct temperature 
is of great importance in this process, and varies with the 
percentage of carbon. High steel, or one with a high per- 
centage of carbon, requires a lower temperature than steel 
with a lower percentage. The steel should be heated to blood- 
red, and then quenched in clean cold water. Any carelessness 
in the process is apt to produce " water "" or " hardening "" 
flaws. Some workers claim that a handful of common salt 
dissolved in the water gives a higher degree of hardness, with 



154 METAL-WORK 

less liability to water flaws. For extreme hardness^ a cooling 
bath of mercury^ or a solution of 1 ]30und of citric acid to 
1 gallon of water, is often used. 

For hardening springs or very small tools, a cooling bath of 
sperm or raw linseed oil is employed. In hardening thin flat 
work there is a great liability to twist on cooling. This can 
be prevented by cooling between two heavy plates. 

Tempering. — Hardened steel is much too brittle for ordinary 
tools, and must have the hardness reduced so as to render them 
elastic. Hardened steel, if heated, softens and loses its 
brittleness. This process of reducing the hardness to inter- 
mediate degrees is called " tempering. "" 

If the hardened steel is brightened and then slowly heated, 
it gradually assumes a pale straw colour, and, if the heating be 
continued, turns to dark straw, then to a reddish-purple, 
followed by dark and light blue. After this stage the metal 
turns grey, and quickly shows a dull red, at which point all 
" hardness '' is removed. The metal thus passes through all 
stages from extreme hardness to softness, and can be arrested 
at any point by removing from the source of heat and quickly 
quenching in water. If the material is found to be too hard, 
the heating process can be continued; but if it is found too soft, 
it is more satisfactory to reharden and commence the process of 
softening again. The colours shown in this process are due to 
a thin scale or oxide, and may be easily removed by rubbing. 

Methods of Tempering. — The simplest and most common 
method of tempering tools (known as " point hardening ") is 
effected by heating the tool for about 2 inches from its cutting 
edge or point to blood-red, and then cooling, by immersion in 
water, for a distance of 1 inch. The extreme end thus becomes 
hardened. The end is now brightened by quickly rubbing 
with a piece of sandstone, and as the heat from the body of the 
tool travels towards the hardened portion the colours appear. 
When the cutting edge shows the required colour, the tool must 
be quickly plunged into water. In this method the hardening 
and tempering are both'performed, but by one heat or operation. 



FORGE WORK 



155 



Tools which have been previously hardened and brightened 
are often tempered by heating with a Bunsen burner, or by 
laying them on an iron plate placed over a gas-stove or forge- 
fire. This method is especially suitable for tools which require 
an even temper throughout, such as screw-dies and screw-plates. 
Taps, twist drills, reamers, etc., which have also to carry an 
even temper throughout their length, are tempered by holding 
the hardened tool inside a length of gas-pipe which has been 
heated to full red, removing the tool at intervals to observe the 
colour. Baths of molten lead or lead and tin are often used for 
tempering articles uniformly. Lead melts at a uniform tempera- 
ture, and by alloying it with various percentages of tin, baths 
with an extensive range of temperature can be obtained. 

Another method employed, when a large number of articles 
are required at a certain degree of temper, is to heat a bath of 
oil to the required temperature, and immerse the hardened 
tools in it long enough to raise their temperature equal to the 
bath, then remove and quench. 

Tempering should always be done in daylight if possible, as 
by artificial light the temper colours are very deceptive. They 
mostly appear farther along the scale, or softer, than is really 
the case, and this should always be borne in mind should it be 
imperative at any time to temper by artificial light. 

Tempering Table. 



Colour. 


Temperature. 


Use. 


Very pale straw 


430 


Hammer faces, razors, surgical instru- 
ments. 


Light straw 


450 


Penknives, milling cutters. 


Medium straw . . 


470 


Boring tools, scissors, shears, cold 
chisels for steel or hard cast-iron. 


Dark straw 


490 


Taps, dies, chasers. 


Yellow-purple . . 


510 


Reamers, firmer chisels, plane irons. 


Light purple . . 


520 


Flat drills, twist drills, table knives. 


Dark purple . . 


550 


Cold chisels for brass or wrought-iron, 
centre-punches, lathe tools, swords. 


Dark blue 


570 


Springs, hand-saws, augers, daggers. 


Light blue 


600 


Screwdrivers, circular saws. 



156 METAL-WORK 

Case-Hardening. — Wr ought-iron and mild-steel are the only- 
metals suitable for case-hardening, which consists of hardening 
the metal for a depth varying from g\ to J inch below the 
surface, leaving the core soft and ductile. The articles to be 
case-hardened are enclosed in an iron box or case fitted with 
an air-tight lid, and packed in powdered animal charcoal, 
such as burnt bones, leather, hoofs, horns, etc. 

The case (from which the process derives its name) with its 
contents is now heated slowly and uniformly to a dull red. It 
is maintained at this heat for a period varying from twelve 
hours to several days, according to the depth of hard skin 
required, after which the case is opened and the contents 
plunged into water. 

A simple process of obtaining a hard skin on these two 
metals consists in heating to redness, rolling in powdered 
prussiate of potash (potassium ferricyanide), and quenching 
in clean cold water. This process renders the metal very hard, 
but only for a depth of about yj^ i^^^ below the surface. 
A compound of equal parts of prussiate of potash, sal- 
ammoniac, and common salt, yields better results on mild- 
steel than potash alone. This latter process is often loosely 
termed " case-hardening,'' but true case-hardening can only 
be carried out in a " case " or " box.'' 

Case-hardening resembles the cementation process of steel- 
making. The product is low carbon steel or iron with an 
outside case of high carbon steel, capable of being hardened by 
heating and plunging into water, and is extremely useful 
where a hard-wearing surface is required in an object which 
is, or might be, subject to sudden shocks. The hard outside 
surface and the soft tough core make it extremely valuable 
in tool work. Typical examples of case-hardening are set 
screw ends, as used in stocks, dies, and lathe-tool holders, 
spanner ends, and holding parts of tap-wrench. 



CHAPTERIXVI 

DEILLING, RIVETING, PUNCHING, SHEARING, AND 

GRINDING 

Drilling. — The drilling of small holes is one of the most 
frequently repeated operations in metal- working. Drills of 
various types are used, the most common being the flat or 
diamond-pointed drill shown at Fig. 135 (figured correct 
proportions) . 




Fig. 135. 

This drill is usually made from a bar of round cast-steel, 
forged flat at the end, filed or ground as shown, and after- 
wards hardened and tempered. The angle formed by the 
cutting edges is usually about 90 degrees, but, as the point of 
the drill must always be in the metal when the extreme point 
of the cutting edge starts to drill, this angle must vary with 
the thickness of metal to be drilled. Thus, when drilling thin 
sheet metal the angle must be considerably more obtuse than 
90 degrees. If this rule is ignored, the result is generally a 
three-sided or elliptical hole. The " relief " or clearance angle 
of the cutting edge varies from 3 to 10 degrees, being sharp or 
fully relieved for soft metals, such as copper, zinc, etc., and 
nearer square for harder metals, such as cast-iron and steel. 
-To enable the flat drill to cut well and accurately to size, the 
cutting edges must be equal in length; otherwise the whole of 

157 



158 



METAL-WORK 




the work is thrown upon the larger edge, and the resultant hole 
is larger in diameter than the width of the drill. 

The chief advantage of the fiat diill is 
that it can be quickly made in the handi- 
craft-room; but it has this great dis- 
advantage, that the diameter of the hole 
cut is reduced every time the drill is 
sharpened, nor can it be relied upon to 
drill a true straight hole, having no 
" body "" to insure its rimning true. 
The point is also inclined to run away 
from the dense or hard atoms of the 
material. This fault is termed " wob- 
bling,"' and is more common when dealing 
with metals which are not homogeneous, 
such as cast-iron and cast-brass. To 
overcome these weaknesses. Sir Joseph 
Whitworth, in the year 1850, experi- 
mented with a form of twist drill, but 
was unsuccessful in producing a practical 
tool. Mr. Morse, of New Bedford, Massa- 
chusetts, U.S.A., then took the matter up, 
.md eventually produced the Morse twist 
(Irill shown at Figs. 136 and 137, which 
lias rapidly become the most popular 
lorm of metal- work drill. The correct 
.mgle of the twist drill cutting edge is 121° 
with the side of the drill, leaving the 
included angle of 118° between the cutting 
edges. The relief or clearance angle (some- 
times termed "lip clearance "") may vary 
from 3° to 10°, as in the flat drill, but new 
drills as supplied from the makers usually 
have a clearance of 5°. Longitudinal 
clearance is obtained by the twisted flutes, 
and body clearance by slightly reducing 
the diameter of the diill except for a small 



/, 





Fig. 136. 

Taper 
Shank 
Drill. 



Fig. 137. 

Parallel 
Shank 
Drill. 



DRILLING 



159 



distance on the edge of the twisted flutes. This form of drill 
is much more expensive than the flat drill, but the quality of 
work is superior. It has also the advantage of always drilling 
a straight hole, and not decreasing in cutting diameter when 
ground. 

The necessity for accurate grinding is even more pronounced 
than in the flat drill, as if not correct an extra strain is put upon 
the flute edges and the sides, frequently causing breakage of the 
chill. A twist drill, if accurately ground, should when vertical 
remain stationary at any point in a hole which was drilled by 
it; not even its own weight should force it to drop through. 

The pin drill (Fig. 138) is used for recessing holes to 
accommodate cheese-head screws, bolt-heads, etc. The ]Din 
on the drill should be of the same diameter as the hole to be 
recessed and in which it is placed. As the drill is fed down, 
the cutting edges on the sides produce the required recess. 
When the drill is in use, the pin should always be lubricated. 






Pin Drill. 
Fig. 138. 



Flat Ended Drill 
Fig. 139. 



Slot Drill. 
Fig. 140. 



The flat-ended drill (Fig. 139) is used for drilling holes 
with a flat bottom, the small projecting point being necessary 
to keep the drill running centrally. This drill is sometimes 
used to square-out the conical bottoms of holes that have 
been drilled out to the required depth by flat or twist drills. 

The slot drill (Fig. 140) is used for cutting slots and key- 
ways. Aflat-bottomed ___^^_^ 

hole is first drilled. The !f i!^^ ^^^- ~^^^^^^^^^^^ 

serted, and as it re- -p^^, 142 

volves the work is 

slowly moved forward, so producing the required slot or keyway. 
The combination centre drill (Fig. 141) is used for drilling 



160 



METAL-WOUK 



the centres of work to be turned in the lathe. It drills and 
countersinks in one operation, thus efiEecting a considerable 
saving of time. 





Fig.' 142. 



The countersinking drill (Fig. 142) is used for'counter sinking 
the mouths of holes to take screws or rivets, and for removing 
the " burr '' from drilled or punched holes. 




Rose Bit Drill. 
Fig. 143. 




Fig. 144. 




Fig. 145. 



Boring Bar. 

Fig. 146. 



The rose hit (Fig. 143) is specially suited for accurate 
work, and is only employed in finishing holes which 
have been previously roughly drilled. It is only suitable 
when used in a vertical position, owing to the difficulty 
of lubricating when used horizontally. Should a hole be 



DRILLING 



161 




drilled a little too small, or if a tapered hole is required, 
a reamer or broach as shown at Fig. 144, is used. This 
tool is usually a round bar of steel with a series of grooves 
cut on its outside surface to form cutting edges. A reamer 
for rough work can be made by drawing-down, in a forge, 
to a slight taper a steel bar of square or 
hexagonal section, then filing up the faces and 
hardening and tempering. The resultant tool, 
however, is not very satisfactory, when com- 
pared with the fluted type, on account of the 
large angle of the cutting edges. The taper is 
generally J inch in 12 inches. As this fine taper 
causes any downward pressure to be converted 
into a strong lateral thrust, the feed of the 
reamer must be very slight. 

The cutter bar or washer cutter (Fig. 
145) is adjustable, and is used for cutting 
washers or large holes in thin plates. 

The boring bar (Fig. 146) is used in 
the lathe for boring large holes. The 
bar is held between the lathe centres, 
and the work bolted to the saddle. As 
the bar revolves, the work is made to 
travel forward or backward as required. 

Drills may be operated in the 
lathe. The drill is held in a 
drill chuck, which is screwed to 
the revolving spindle, and the 
work is fed up by means of the 
poppet. They are also operated 
by a breast drill (Fig. 147) or 
by means of a drilling machine, 

of which there are several types. For use in the handicraft- 
room a bench drilling machine, as Fig. 148, is sometimes 
used, but the wall or post type, as shown at Fig. 149, which 
can be screwed to the wall, will be found most convenient. 

11 




Fig. 147. 



162 



METAL-WORK 




Fig. 148. 



DRILLING 



163 




Fig. 149. 



164 



METAL-WORK 



In drilling, the point which marks the centre of the hole 
should be accurately marked with the centre-punch, and, if 
extreme truth of position is required, a circle marking the 
outside of the hole should be described on the metal with the 
dividers, and four equidistant dots slightly punched. The 
drill should now be allowed to just enter the work, and then 
be withdrawn to check the centre with the four dots. If the 
drill has run out of the centre, the hole must be drawn over 
with the round-nose chisel. 

Rivets and Riveting. — Riveting is a method frequently 
employed in joining metals. Rivets can be arranged either 
to render the parts immovable, or to act as a pivot on which 




Pan . Countersunk . 

Fig. 150. — Forms of Rivet Heads. 

they may revolve. Four different t3rpes of rivet heads, 
shown at Fig. 150, are in common use, but the snap and 
countersunk are mostly used in the handicraft-room. 

The snap head is nearly a hemisphere in form, the diameter 
of the head^being slightly less than twice the diameter of the 



KIVETING 



165 



rivet. The conical head is a true cone with a base equal to 
twice the rivet diameter, and a height equal to the rivet 
diameter. The pan head has its greatest diameter equal to the 
rivet diameter multiplied by 1-5, and sloping to rivet diameter 



^-^ ^ \pitchJ 




Single. 



7- 




Zig-Zag 





•) 4 4i# 



u_p-*i 




Butt 



Z) 



Fig. 151. — Rivet Placings and Spacings. 

multiplied by 1'25. The height is slightly less than the rivet 
diameter. The countersunk head is usually formed so that its 
height equals half the thickness of the plate to be riveted and 
an angle of 60 degrees. 
Fig. 151 shows the various ways of placing and spacing rivets. 



166 METAL-WORK 

A rivet consists of head, shank, and tail, the latter being 
formed by riveting up. A length equal to the rivet diameter 
is usually allowed for this purpose. The diameter of the 
rivet must vary with the thickness of the plates to be joined, 
so that the shear strength of one rivet equals the tensile 
strength of the plate between two rivets. 

A general formula for determining the diameter of rivets is — 

when D = diameter of rivet, 
t--= thickness of plate. 

Another formula, which also gives the distance between 
the centres of the rivets, or, as it is termed, the " pitch,"" 
together with the necessary overlap, is — 

d=t + ^Q inch, 
p^l'Qt+l^ inches, 

Zr=3^+ 1-1 inches, 
when d =^ diameter of rivet, 

t = thickness of plate, 
^= pitch, 

Z=lap of plates. 

Large work is always riveted up with the rivets heated to 
redness, when the contraction of the rivet assists in drawing 



EiG. 152. 

the plates firmly together, but in the handicraft-room " cold 
riveting " is possible in the small sizes of plates and rivets 
employed. 

When riveting, a firm bedding must be employed. This 
is usually obtained by using a rivet-set or bolster (Fig. 152), 
which is gripped firmly in the vice. The rivet is spread by 



RIVETING 167 

blows from the ball-pane of the hammer, which should be 
dehvered with a glancing motion. The blows mnst not be 
too heavy, or the rivet may bend over or split. In counter- 
sunk riveting the hammered end is filed off flush with the 



Fig. 153. 



face, while other forms are finished with a " set '' of the shape 
desired. The tool is j)laced over the hammered end of the 
rivet, when two or three sharp blows shape up the required head. 
Rivets are made from brass, copper, aluminium, wrought- 
iron, and mild-steel, and are sold by weight. 




Fig. 154. 



Fig. 155. 




Fia. 15G. 



GRINDING 169 

Punching and Shearing Machines. — Appliances for punching 
and shearing plates and bars are essential in the handicraft- 
room. A combined machine has the advantage of saving 
space, and a useful machine is shown at Fig. 153. Should it 
be deemed advisable to have separate machmes, the punching 
bear at Fig. 154 and the bench shears at Fig. 155 will be 
found convenient and of sufhcient power. 

Grinding. — A grindmg appliance is one of the indispensable 
tools in the handicraft-room, as only by its use can many of 
the other tools, such as scribers, centre- punches, chisels, and 




Fm. 157. 

lathe tools, be kept in proper working order. A grindstone, 
as shown at Fig. 156, is durable and cheap, but it has the 
disadvantage of occupying a considerable amount of floor 
space, being dirty in use and very slow in cutting. Its only real 
advantage is that, being run in water, when grinding tempered 
tools the friction does not generate heat. The grindstone 
is replaced in many handicraft-rooms by the bench grinder 
(Fig. 157), which is compact, of high speed, and quick cutting. 
This machme can be fitted with either emery or carborundum 



170 METAL-WORK 

wheels. Carborundum^ being extremely hard^ is useful for 
removing the hard skm from cast-iron and the rough surfaces 
from forge work and brazed joints. Being of high speed and 
running dry, great care must be taken in dealing with tem- 
pered tools. They must be frequently dipped in water or 
cooled on wet rag, otherwise the heat generated will soften 
the edge. 

The most suitable grade of grindstone for the handicraft- 
room is " blue grit "" or " middle Bilston/' and Grade 4 
" medium soft "" for carborundum wheels. An attachment 
can be obtained for bench grinders which simplifies the process 
of grinding twist drills by holding them in a correct position. 



CHAPTER XVII 



_A. . 

Charging Hole 



CASTING 

Castings, while seldom coming into the actual operations 
of the handicraft-room, enter largely into the equipment, 
forming part of most 
machines and appli- 
ances. Many metals 
have the property of 
casting readily into 
moulds, but pig-iron 

and brass are most Charging Platform^, 
commonly used for 
this purpose. 

Pig-iron for cast- 
ings is melted in a 
cupola (Fig. 158). 
On account of the 
irregular demand for 
castings, cupolas are 
usually relit daily. 
The charge is made 
up as follows: First 
7 hundredweights of 
coke, then 1 ton of 
pig-iron, and after- 
wards 2 hundred- 
weights of coke and 
1 ton of pig - iron 
alternately until 
fully charged. The 




SECTION ON 
A.B 




Tap Hole 

Ground Line> 
Blast Pipe 

lag Hole 



Fig. 158.— Cupola 



171 



172 METAL-WORK 

ca]3acity varies from 3 to 20 tons of pig-iron, and the time 
occujDied in running down the charge is from three to six 
hours. When the charge is completely melted, the cupola 
is tapped and the molten metal conveyed in ladles to the 
prepared moulds. 

Brass is usually melted in crucibles in a furnace, as shown 
in Fig. 10. The crucibles are generally made from fireclay 
mixed with powdered graphite (blacklead). The mixture is 
termed " plumbago."' These crucibles will withstand very 
high temperatures, and very rarely crack during the cooling 
process. Fireclay crucibles are sometimes used on account 
of their cheapness, but they are only capable of dealing with 
four to five charges, whilst those made of plumbago are often 
quite good up to thirty charges. The capacity of the crucibles 
varies from 2 to 60 pounds of metal. 

Good clean castings depend upon three points : 

1. Quality of the patterns. 

2. Quality of the metal. 

3. Skill and care of the moulder. 

The pattern should be made of good, well-seasoned, straight - 
grained wood, which is not liable to twist or shrink. Yellow 
pine {Pinus strobus), mahogany, or boxwood, are commonly 
used; but when a pattern is likely to be subjected to hard and 
constant wear, it is often made of cast-iron, brass, or an alloy 
of lead and tin. The pattern must also be made with slightly 
tapered rather than parallel sides, to allow easy removal 
from the loam without damage to the mould. They must 
also be proportionately larger than the required casting, to 
allow for contraction of the work in cooling. The amount of 
contraction varies with the shape of the object and the metal 
used, but a general allowance of J inch to the foot is 
sufficient. Sharp internal angles should be avoided, and the 
whole pattern coated with spirit varnish or blacklead, to 
keep the surface smooth and prevent dampness from the loam 
affecting the wood. If these points are observed, together 



CASTING 173 

with reasonable care, the pattern will leave the moulding sand 
readily without breaking or roughening the mould and so cause 
defects in the finished casting. 

Simple castings are made in two-part boxes, called " flasks/' 
These consist of a pair of shallow cast-iron frames, one of 
which has a lug with a hole through it (called the " eye ""), 
and the other a lug with a pin (called the " peg ""). The peg 
fits into the eye, and allows the flasks to be taken apart and 
replaced in exactly the same position. When in use, the 
frame containing the eye is placed upon the ground and the 
peg frame fitted down upon it. In brass foundries the bottom 
box is called the " eye " side, and the top the " peg "" side; 
but in iron foundries they are known respectively as the 
" cope " and the " drag."" 

Two kinds of moulding sand are used in casting — green- 
sand and loam. Greensand is obtained from river-beds in 
the neighbourhood of the chalk and coal-measures, the best 
being obtained from the London Basin. Greensand from 
near coal-measures often contains particles of iron, which are 
liable to melt and reduce the quality of the casting. Loam 
is a mixture of clay and rock-sand, ground in a mortar-mill 
together with horse-dung, chaff, or cow-hair, to bind it. For 
large, rough castings greensand is used, but for fine work 
either loam or a mixture of loam and greensand is used. 

Cores are made from coarse but adhesive sand, which is 
often a mixture of rock-sand, sea-sand, and clay. 

Parting sand, which is used for dusting between the flasks 
before fitting together, consists of finely powdered brick-dust 
or blast-furnace cinder. 

The operation of casting will be best explained by con- 
sidering a definite example, and for this purpose the casting 
of the screw-jack body (Model 16) in the course of work is 
taken. 

The pattern for the screw-jack body will be similar in shape 
to the finished casting, except that the hole is omitted and 
is replaced by a circular core print (Fig. 159), which is equal 



174 



METAL-WORK 



in diameter to the cast hole. In addition to this pattern, 
a coLre box is provided consistmg of two " hollowed-out "" 
blocks of wood, which, when placed together, give a hole 
equal in diameter to that required in the casting, and in length 
equal to the distance across the core prints. The bottom 
flask is now laid firmly on the ground, filled with sand, and 
the pattern firmly pressed into it until the centre line of the 
pattern coincides with the top of the flask. The face of the 
mould is then cleaned off and dusted with parting sand, the 
top flask placed in position, and afterwards filled with sand 
and firmly rammed. The gates, vents, and risers, are then 



Pouring Gate 



Core Print 
Vent 




Section through Casting Boxes. 

Core Print' 
Fig. 159. — Casting foe Screw-Jack Body.. 

taken out by wires or tubes, the top flask carefully lifted off, 
and the pattern removed. The parting sand allows the top 
flask with half the moulded pattern to be removed without 
injury to the bottom portion. In many castings the junction 
of the two half -patterns may be noticed. This is due to the 
slight rounding of the edges of the mould during the finishing 
off, or to the failure to key the two flasks closely together. 

The core is now required to form the hole. This has been 
previously formed by filling the core box with damp sand, 
and, after removing it from the box, placing it in a stove to 
dry and harden. This core is placed in the core prints, which 
fix its position, and the whole of the mould is dusted over with 



CASTING 



175 



fine powdered charcoal^ any excess being blown out with 
small hand-bellows. The top flask, after thoroughly drying, 
is again placed in position, and all is now ready for the pouring 
in of the metal. The drying process is important, as if mois- 
ture be left in the mould the molten metal will cause steam 
to be generated, and consequently blow-holes to be formed 
in the metal, or, if the moisture be excessive, sufficient steam 
may generate to blow the mould to pieces. The object of 
the riser is to allow a portion of the metal to run through the 
mould and clear away any dust or sand which may have fallen 






Core Box 




i 


F 


• 






• 



Closed 



Open 



H- 




Fig. 160. — Casting of Small Hand -Wheel. 

A, B, Top and bottom moulds; 0, core; D, mould; E, pouring gate; F, core 
box; G, pattern; H, top box; J, bottom box; K, vents and risers. 

into the mould when the two flasks were flnally placed to- 
gether. It also assists in the ventilation of the mould and 
prevents air-locks. 

In small thin castings a process is sometimes carried out 
in which a core is covered with wax equal to the thickness 
and shape of the finished casting. This is then covered with 
plaster of Paris or clay, and during the baking in the stove 
which follows the wax disappears, leaving the mould of exact 
size, ready for casting. Fig. 160 shows an'example of casting 
a small hand- wheel. 



176 METAL-WORK 

Chilled castings have very hard and durable faces, due to 
being cast into iron instead of sand moulds. When the 
molten metal meets the cold iron of the mould, it cools rapidly 
and forms crystals of hard, white cast-iron on the faces. 

Burning on a casting that has been broken is often carried 
out by heating the fractured ends to red-heat, dusting with 
borax for a flux, and laying the parts, properly joined, in a 
channel-shaped loam mould. Liquid cast-iron is then run 
through the mould over the portions to be joined until they 
become plastic, when the flow of metal is stopped and the 
casting allowed to cool. If the operation is efflciently per- 
formed, a good joint is effected, which gives the same ring 
when struck as a new casting, thereby showing that the ends 
have perfectly united. 

Cracks, blow-holes, and flaws in castings are frequently 
" stopped " with a composition known as Beaumontague, 
which consists of equal parts brimstone, pitch, sal-ammoniac, 
resin, and beeswax, mixed with about 5 parts fine cast-iron 
filings. 

The processes of moulding and casting may be carried out 
in the handicraft-room by using an alloy of lead and tin in 
place of cast-iron. The resulting casting can be used for a 
preliminary lesson in lathe work. 



CHAPTER XVIII 

LATHES AND LATHE WOKK 

The lathe, besides being the oldest, is regarded as the 
most useful, of all machine tools. Its action is most fascinating 
to beginners, and its endless possibilities appeal to advanced 
pupils. A great many mechanical operations can be carried 
out in the lathe, but the most common uses to which it is 
put in the handicraft-room may be classified thus — - 

1. Turning to circular form. 

2. Drilling and boring. 

3. Surfacing or facmg (producing a plane surface). 

4. Screw-cutting. 

A thorough knowledge of its construction, and an insight 
into the functions of its various parts are essential if the full 
value of its mechanical principles, and of the power ex- 
pended in driving it, is to be obtained. 

Figs. 161 and 162 show a typical example of a plain non- 
screw-cutting lathe suitable for a school workshop. The 
bed (A) is supported upon two standards (B) . These standards 
also carry the treadle motion (0), to which the cone pulley (D) 
is keyed, and from which the belt or band transmits the 
motion to the mandril pulley (E) . This is keyed to the lathe 
mandril, which is supported by the main bearing (F) . The 
casting which carries these bearings is known as the " fast 
headstock casting,'' and the whole arrangement — pulleys, 
bearings, and mandril — are termed the " fast,'' " front," or 
" mandril " headstock. All lathes are fitted with a second 
stock (G), which is known as the " loose " or " back " head- 

177 12 



178 METAL-WORK 

stock, " tailstock,- " deadhead,- or " poppet.- The spindles 
or mandrils of these two stocks carry the centres {H) upon 
which the work is supported for ordinary turning. J is the 
" face - or " catch plate," which is screwed to the mandril 




nose, and carries the driver {K), which transmits the motion 
to the work by means of the carrier' (L) . The " tee " rest (if) 
is to support the tool when hand-turning, but this method of 
lathe work is seldom employed in the handicraft-room, owmg 



LATHES AND LATHE WORK 



179 



to the physical force and skill required, and also to the danger 
attending its use. The slide rest (N) is a mechanical device 
for firmly holding and guiding the tool, thus removing the 
dangers attending the tee rest. By means of the slide rest the 
tool can be moved parallel, at right angles or at an angle to 
the centres. It should be noted that the fast headstock is 




H 



-/' 



Work 



Enlarged View of 
'•^ Face Plate and Carrier. 




Fig. 162. 

bolted permanently to the bed, whilst the loose headstock 
and slide rest are movable, being secured where required to 
suit the length of the work by means of a nut and screw. 

Fig. 163 shows a vertical section through the fast head- 
stock of a plain lathe. It will be noted that the front of the 
mandril runs in a conical bearing, the journal on the mandril 
being cut to fit the bearing. The back-end is supported by 
an adjustable screw, called the "thrust-pin/' This arrange- 



180 



METAL-WORK 



ment allows the wear in the bearing to be taken up by the 
conical part of the mandril, by simply advancing the screw. 




Fig. 163. 



The great advantage of this type of bearing is that it is possible 
to make all adjustments for wear in the bearing parts without 




Fig. 164. 



altering the height of the centre, which must always be 
kept in true alignment with the centre of the loose headstock, 
otherwise parallel turning becomes impossible. Fig. 164 



LATHES AND LATHE WORK 



181 



shows the complete headstock. The front end of the mandril, 
known as the " nose/' is usually screwed to take the chucks 
and face plates, and has a tapered hole to receive the centre. 





SECTION 

Fig. 165. 



END VIEW. 
Fig. 166. 



The Loose Headstock of a plain lathe, shown in section at 
Fig 165, consists of a main casting which is bored to receive 
the sliding barrel, the outside end of which receives the centre. 
This sliding barrel is fitted with an internal square thread, 
which engages in the feed- 
screw operated by the hand- 
wheel. This arrangement 
is a convenient method of 
making the finer adjust- 
ments of the centre to the 
length of the work. It will 
be observed that by turning 
the hand-wheel the centre 
advances to the correct 
position, on reaching which 
it is locked by the set-screw. 

To prevent the barrel from turning when the hand-wheel is 
operated, a small grub-screw is fitted through the casting, 
and engages in the key way which is cut along the length of 
the barrel. Fig. 166 shows the complete loose headstock. 




Fig. 167. 



182 METAL-WORK 

The Slide Rest (see Figs. 169 and 170) consists of a "tool 
post'" or "head"' which secures the tool. This head can be 
revolved on the centre bolt, and so present the tool to the work 
at any deshed angle. The centre bolt secures the head to the 
top sliding carriage (called the " top-slide"'), which is operated 
backwards or forwards by means of the top screw. This top- 
slide is usually mounted on a circular table, which is fixed 
centrally by a round-headed pin and clamped into position 
by two bolts and nuts. This arrangement gives the top-slide 
a circular motion, so that it can be swivelled to any desired 
angle for taper turning. 

The whole of the top-slide is carried on the bottom-slide, 
which gives a combined movement of both parts across the 
lathe bed. The action of the top-slide is known as the 
traverse movement, and that of the bottom-slide as the 
surfacing or feed movement. The under -face of the bottom- 
slide is fitted to the lathe, and the whole rest held in position 
by means of a bolt, nut, and washer. 

Adjustment for wear in the slides is effected by means of 
chipping strips, as shown at Fig. 168. The slides are made 

dovetailed in section, and 
the carriage cast and planed 
so that one edge fits into 
the dovetail of the slide, 
whilst the other edge is 
made with a square fillet. 
Between this fillet and the 
side of the dovetail a small 
chipping strip is fitted, and 
held in position by two or 
three round-headed screws, which attach it to the carriage. 
The screw holes in the strip are slotted and allow for adjust- 
ment, as two or three grub -screws, which pass through the 
fillet, press the strip against the outer edge of the dovetail. 
This arrangement of chipping strips is employed in all sliding 
X^arts of machine tools to take up wear. 




LATHES AND LATHE WORK 183 

The lathe bed is made of cast-iron, carefully planed and 
scraped to a true surface. The mandril should be of the best 
cast-steel, to resist wear, and the bearings of gunmetal, 
which gives an ideal rubbing surface. The thrust-pin is 
made of mild-steel, with the rubbing end case-hardened. 
The loose headstock and hand-wheel are of cast-iron, with a 
mild-steel barrel and screw. The carcase of the slide rest is 
made of cast-iron, with mild-steel traverse screws. The nuts 
for these screws are of brass, as, being the softer metal, they 
take practically the whole of the wear, and it is cheaper to 
replace nuts than screws. The set-screws for holding the tool 
are of mild-steel, with the ends case-hardened to prevent 
burring. The standards are of cast-iron, and are commonly 
cast to A form for strength and stability. The treadle and 
cranks are forged from mild-steel. 

The Screw-Cutting Lathe. — The screw-cutting lathe, two 
types of which are shown in Figs. 169 and 170, in addition to 
possessing all the advantages of the plain lathe, can also, by 
the inclusion of certain necessary adjuncts, be used for cutting 
screws of any pitch or section. As a rule this lathe is employed 
in the making of all screws above | inch diameter, and for 
all square, knuckle, or buttress threads of all sizes. The 
additions necessary to perform these operations are a guide 
or lead screw, set of change-wheels, back-gear. The guide 
or lead screw runs the entire length of the bed, and is capable 
of being put into gear with the slide rest or run indepen- 
dently. 

The rotations of the lathe spindle or mandril are transmitted 
to the lead screw in any ratio by means of interchangeable 
toothed wheels called " change- wheels.'" A complete set of 
these wheels, as supplied with a screw-cuttmg lathe, consists 
of 23, rangmg from 20 to 120 teeth per wheel, increasing by 
fives, with duplicates of the 20 and 40 wheels. By means 
of these wheels the ratio of rotation between the mandril 
and the lead-screw can be controlled, so as to allow the 
accurate cutting of any pitch within their range. It is also 



184 



METAL-WOPvK 




Fig. 169. 



usual to suppty a wheel with 127 teeth which can be used 
in adapting the speed to the cuttmg of metric threads. 

Most screw-cutting lathes are now fitted with a gap-bed 



LATHES AND LATHE^WORK 



185 




M^tKSI 



and in some cases with a gap-piece. This gap allows much 
larger work to be accommodated than is possible with a 
straight bed. As an instance, a 4|-inch centre lathe with a 
gap-bed can take work 18 inches in diameter, provided the 
length of the work allows it to run clear in the gap. This is 
a distinct gain, which is valuable. 



METAL-WORK 




In the plain lathe it should be observed that change of 
speed is effected by means of the cone pulley, but a distinct 
feature of the headstock of the screw-cutting lathe shown in 
Fig. 171 is the back-gear. This gives the mandril a much 



LATHES AND LATHE WORK 187 

lower speed, and consequently greater power, than can be 
obtained by direct drive on the smallest step of the cone 
pulley. 

The back-gear consists of a large and small cog-wheel, called 
the " wheel " (large) and " pinion '' (small), fitted on the 
mandril, and a corresponding wheel and pinion cairied on 
a back-shaft, which is fitted in bearings parallel to the main 
bearings of the mandril. The mandril pinion is cast on, or 
secured by some other means to the cone pulley, and both 
are free to revolve on the mandril, whilst the mandril wheel 
is securely keyed to the mandril. The back-shaft pinion 
and wheel are both securely fixed on, and revolve with, the 
back-shaft. When the back-gear is in use for low speeds, the 
motion is transmitted from the mandril pinion to the back- 
shaft wheel. This wheel, being fixed to the back-shaft pinion, 
must revolve with it, and in doing so drives the mandril wheel, 
which, being keyed to the mandril, makes it revolve. 

The reduction in speed due to this gearing depends on the 
relative proportions of the wheels and pinions, and the usual 
ratios give a reduction varying between one-sixth and one- 
ninth of the speed ungeared. For direct driving the back-gear 
is thrown out of action by eccentric bearing parts, so that a 
movement of the lever puts the system in or out of use. A 
set-pin passing through a hole drilled through both casting and 
back-shaft holds the gear in the required position. When the 
back-gear is out of action, the motion is carried direct by attach- 
ing the mandril wheel to the pulley by a shding bolt or set-pin. 

The main bearings of a screw-cutting lathe differ somewhat 
from those used in a plain lathe. Fig. 172 shows a vertical 
section through the main bearings of a 4 J -inch centre screw- 
cutting lathe . The bearing parts of the mandril are conical, an d 
revolve in gunmetal bearings. The front cone is part of the 
mandril, but the back cone is hollow and slides on a feather 
key, so that, whilst it must revolve with the mandril, longi- 
tudinal movement is possible. A fine screw is cut on the 
mandril immediately behind the back cone, to which is fitted 
a pair of circular nuts, by tightening which both cones are 



188 



METAL-WORK 



adjusted into their bearings, and the alignment of the mandril 
and centre maintained. 

It is usual to make the front cone to a greater angle than 
the back one, the reason being that under the pressure of the 




€^M 



Fig. 172. — Vertical Section through Bearings of 4^-Inch Centre 

Lathe. 

cut the wide angle is not so liable to lock or bind, and the 
narrower angle of the back cone is more sensitive for adjusting. 
The pressure of the cut or thrust is taken from the end of 
the mandril and thrown on the tail or thrust- 
pin, which is made of hard steel and screwed 
with a very fine thread to allow careful 
setting. Without the thrust-pm the mandril 
would be sure to bind when the lathe was 
cutting towards the fast headstock. It is 
most important that the thrust-pm be con- 
stantly and well lubricated when the lathe is 
running. 

The arrangement for locking the barrel in the loose headstock 
differs from that usual in the plain lathe, and is shown at 
rig. 173. It will be noticed that the clamp-screw, in addition 




Fig. 173. 



LATHES AND LATHE WORK 



189 



to binding the barrel, also acts as a key to prevent its revolving. 
Figs. 174 and 175 show the complete fast and loose head- 
stocks of the screw-cutting lathe. The slide rest of the screw- 




FiG. 174. 

cutting lathe is much more complicated than the type used 
in the plain lathe, as some arrangement must be made whereby 
it can be locked to the lead-screw. This is effected by carry- 
ing the bottom -slide 
over the bed, to which 
it is fitted in the usual 
way by chipping strips. 
The parts resting on 
the bed are known as 
the " saddle.'' 

A front plate, called 
the " apron,'" is secured 
to the saddle, and 
passes in front of the 
lead - screw. A half- 
nut is secured to the 
apron, and is arranged so that it can be engaged or dis- 
engaged from the lead-screw. When the tool has come to 
he end of a cut in working, this half -nut is disengaged ., and 




Fig. 175. 



190 



METAL-WORK 



the saddle wound back quickly by means of a rack, which is 
fixed to the bed-plate, and a small pinion, which is fitted to 
the apron. 

Fig. 176 is a section showing the details of clamp nut, apron, 
and saddle. The transmission of the motion from the mandril 
to the lead-screw is effected by arranging the change-wheels 



Saddle 





Fia. 176. — Alternative Method of connecting Saddle to 

Lead -Screw. 

on the quadrant which is fitted to the top end of the lathe. 
This quadrant is free to move through an angle of 90 degrees 
about the lead-screw, and is fitted with two slots, into which, 
at any point, studs can be bolted to accommodate the various 
change-wheels required. 
There are three methods in general use in handicraft-rooms 



LATHES AND LATHE WORK 



191 



for holding and driving work in the lathe. The first, and 
perhaps most common, method is to hold the work between 
the centres, and to drive it round by the driver and carrier. 
When this method is employed, the work must be accurately 
centred. The end of the work should be filed up, and when 
the position is obtained it 
must be accurately punched. 

Many appliances are in 
common use for finding the 
centre of rods and bars, but 
most workers, except for 
very exact work, prefer to 
judge it with the eye. This 
method is quick, and with 
a little practice the eye can 
be trained to locate the 
position sufficiently accurate 
for most practical purposes. 

The centering square (Fig. 
177), of which there are 
many shapes, which all de- 
pend upon the same principle, 
is perhaps the most accurate 
tool for centering a rod. 
The square is made with 
three arms, with the centre 
arm bisecting the angle made 
by the other two. When in 
use, the rod is placed in the 
fork or angle, and a line 
drawn across the end of the 
rod by the aid of the centre 
arm. The square is now moved through a quarter-circle, 
and another line drawn. The intersection of these two lines 
marks the centre. 

The scribing block, vee block, and surface plate, are also 




Fig. 177. 



192 



METAL-WORK 



often used for centering work. The vee blocks are laid on the 
plate with the bar resting in the vee notches. The scriber 
is then fixed as nearly as possible to the centre of the bar from 

the surface of the plate, 
and a line scribed. The 
bar or rod is then turned 
a quarter - revolution, 
and a second Ime scribed, 
this process being re- 
peated in each quadrant. 
The small square formed 
by the intersecting lines 
(Fig. 178) encloses the 
centre, which can now be 
judged quite accurately. 
Another tool for 
locating the centre is 
the bell centre punch 
(Fig. 43, p. 99), but it has 
never found much favour. When the centre has been found, 
a small hole, about J inch diameter and -f^ inch deep, should 
be drilled up the bar. Fig. 141 shows a special drill for lathe 




Centering 
Square 



<- — ^ 

Fig. 178. — Methods of Centering 
FOR Lathe. 




centres. This hole gives the centres a good hold, and at the same 
time prevents burring. Centre turning should never be at- 
tempted on the punched centres without drilling, as, in addition 
to damage to the lathe centres, the work often runs out of truth. 



LATHES AND LATHE WORK 



193 




Fig. 180. 




Fig. 181. 



13 



194 METAL-WORK 

The carrier (Fig. 179) is made in many sizes to accommodate 
bars of different diameters. Care must be taken that the 
driver always strikes against the tail of the carrier, as, should 
the pressure be exerted against the screw when heavy cuts are 




■Fig. 182. 




Fig. 183. — Section. 



being taken, a bent screw is sure to result. When usmg the 
carxier on soft metals or finished work, a small strip of thm 
copper or zinc between the carrier and the work will prevent 
damage. Carriers are made of cast-iron or mild-steel. The 



LATHES AND LATHE WORK 195 

latter material comes out a little more expensive, but always 
gives more satisfaction in the handicraft-room. The nose of 
the screw should always be case-hardened, otherwise it quickly 
burrs over. 

Fig. 180 shows another pattern of carrier. 

The second method of holding and driving is by securing 
the work in a " chuck/' which is screwed to the mandril 
nose. In using the lathe for boring this method is most 
convenient. 

Chucks are of two classes — independent and self-centering. 
The independent chuck (Fig. 181) derives its name from the 
fact that each jaw moves separately, which makes it invaluable 
for holding work of irregular form. In the self-centering 
chuck (Fig. 182) the jaws move together, and always con- 
centric to the lathe man- 
dril. Both types are made 

with two, three, four, or /W^^g HARTFORD. MWAiiiir^iS 
six jaws, and are classi- 
fied by extreme outside 
diameter, number of 
jaws, and type, such as 
— 8 inches, four -jaw inde- 
pendent chuck; or 6 in- ^'-^HMBi^i^^iaBiiiM 

ches, three-jaw self -center- ^ ,g, 

ing chuck. Small two -jaw 

self-centering chucks (Figs. 184, 185) are frequently used for 
holding drills or fine work, and are termed " drill chucks."' 
These are classified by the maximum diameter they will grip. 
A J-inch drill chuck will grip drills from the smallest possible 
size up to h inch diameter. Chucks are made from mild-steel 
in the small sizes, and of cast-iron or mild-steel when of large 
diameter. 

A third method of holding and driving in the lathe is a 
combination of the two previous methods. One end of the 
work is held in a chuck, and the other end supported by the 
back centre. This method is only employed for work, such 




196 



METAL-WORK 



as long bars of large diameter, which cannot conveniently be 
dealt with by either of the previous methods. 




Fig. 185. — Interior Mechanism op Drill Chuck. 

Lathe Tools. — Lathe tools are forged from the best cast-steel, 
and should be hardened and tempered to a light straw colour. 




2. Roughing Tool, 6. Finishing Tool. 10- Screw Cutting Tool 

Cast Iron. Wrought Iron or Mild Steel. 




fZJ 



J 



3. Roughing Tool, 7. Knife Tool, 

Wrought Iron or Mild Steel. Right Hand. 




11. Parting 
Tool. 



4. Finishing Tool. 
Brass. 



"\ 




12. Spring Finishing Tool. 
Fig. 186.— Lathe Tools. 



8. Knife Tool, 
Left Hand. 



LATHES ANT) LATHE WORK 



197 



There are numerous forms; the most common are shown 
in Fig. 186, and their clearance angles are given in the 
following table: 



No. 


Description. 


Clearance Angles. 


Top. 


Side. 


Front. 


1 


Roughing — -brass . . 





5 


15 


2 


,, cast-iron 


5 


5 


10 


3 


,, wrought-iron or steel 


30 


5 


10 


4 


Finishing — brass 








7 


5 


,, east-iron 








10 


6 


,, wrought-iron or steel. . 


15 


10 


10 


7 


Knife tool — right hand 


15 


10 


10 


8 


„ left hand 


15 


10 


10 


9 


Boring 


10 


15 


15 


10 


Screw-cutting 





10 


15 


11 


Parting or cutting off 





2 


7 


12 


Spring finishing 





5 


5 


13 


Side tool — left hand 


) Angles as for roughing 


14 


,, right hand 


j tools 



Front tools may be vee- or round-pointed. In the former 
case the vee is usually about 60 degrees. Screw-cutting tools 
must be equal in angle and shape to the thread recess to be 
cut. 

The term " rake " is often used to imply clearance angles — 
i.e., top-rake, side-rake, or front-rake. 

Tool-Holders. — Tools forged from the solid are now to 
some extent being superseded by small self-hardening steel 
cutter bars. These are held firmly by a screw in a stout steel 
bar known as a " tool-holder/' of which two types are shown at 
Figs. 187 and 188. When using tools of either type, it is of the 
utmost importance that the top edge of the tool should coincide 
with the centre line of the headstock. Should the tool be too 
low, it tends to draw in and cause " chattering,'' which gives 
rise to chatter-marks on the work. With this fault there is 



198 



METAL-WORK 



also danger of breakages. Should it be too high, the tool tends 
to dig in, or if much too high refuses to cut, as the cutting edge 
cannot reach the work. 




Fig. 187. 




Fig. 188. 



Common Types of Lathe Work executed in the 
Handicraft-Room. 

Parallel or Plain Turning is done by setting the top-rest 
parallel with the centres. The bottom-slide is used to give 
the necessary amount of " cut/' and the top-rest for traversing 
the tool along the work. Should the work consist of a number 
of cylinders of differing diameter, each one is cut down to size 
with the roughing tool, and the shoulders then squared with the 
knife tool, using either right- or left-handed type as required. 

Taper Turning can be effected by setting the top-rest to the 
required angle, or, as is possible with some types of lathe, by 
settingjthe back^centre][out of alignment. 



LATHES AND LATHE WORK 



199 



Ornamental or Convex and Concave Turning is effected by 
operating both handles of the slide-rest to give the necessary 
curves. 

Facing or Surfacing. — In this type of v^^ork the exercise 
must be held in the chuck. The top-rest is used to apply the 
cut, and the bottom-rest to carry the tool across the work. 

Boring is the term used to imply internal work. When 
boring in the lathe, a hole must be first drilled or cast in the 
work. This hole can be enlarged to any diameter, and may 
be parallel, tapered, or stepped. 

Screw-Chasing is the name applied to the operation whereby 
screw-threads are cut in the lathe by the aid of screw-chasers 
(Fig. 189). The tools go in pairs generally, one 
for cutting external threads, and one for internal 
threads. 

When using the chasers, the bolt or blank must 
first be turned or bored to the correct diameter. 
A chaser of the correct pitch for that diameter 
is then taken, and, resting on the tee rest, the 
tool is pressed lightly against the revolving work, 
and must advance the pitch, or width of one 
thread, during one revolution. This is largely a 
matter of practice, as, should the tool advance 
too slowly, a number of parallel rings will most 
probably be formed, and if too fast the thread 
goes out of pitch. Should the movement be 
irregular, the thread produced is also irregular, 
and known as a " drunken screw. "" 

Screw-Cutting. — Screw-cutting in the lathe is regarded as 
the most interesting and scientific of all turning processes, and 
should only be attempted by pupils who have thoroughly 
mastered the common uses of the machine. The tools used 
for screw-cutting must correspond in section to the recess of 
the thread to be cut. They may be forged from the solid, but 
the tool-holder is particularly suited for this type of worjs, 



m 



Fig. 189. 



200 METAL-WORK 

Use of Change-Wheels. — If the lead-screw of a lathe is con- 
nected to the mandril so as to revolve at the same rate, and the 
tool is coupled to the lead-screw, it will be seen that the tool 
will cut a screw on a rod which is fixed between the lathe 
centres of equal pitch to the lead- screw. Should the lead- 
screw revolve at twice the speed of the mandril, a screw of 
double the lead-screw pitch, or half the number of threads 
per inch, would be produced. 

The rules which control the calculation of the change- 
wheels for cutting to any pitch are fairly simple, as will 
be seen. 

First find the number of threads per inch on the leading 
screw of the lathe to be used, and the number per inch it is 
required to cut. These figures will show the ratio between the 
speed of the mandril and the speed of the lead-screw, and the 
same ratio must be maintained between all the " driven "" and 
" driving "" wheels. Remembering this rule, the wheel ratios 
can be obtained by the following formula : 

number of threads per inch on lead-screw 
number of threads per inch to be cut 
number of teeth on mandril wheel 

number of teeth on lead-screw wheel. 

Care must be taken that the pitch in each case is reckoned 
in threads per inch. 

To take an example, let it be supposed that it is required to 
cut twelve threads per inch on a lathe with a leading screw of 
four threads per inch. 

Number of threads per inch on lead-screw == 4 
„ „ „ „ to be cut = 12 

This gives four teeth on the mandril wheel and twelve on 
the lead- screw wheel. But as wheels of this size are not in the 
set (twenty teeth being the smallest, and advancing by fives), 
the size must be increased and the ratio maintained. This can 
be done by multiplying each by ten, giving 40, 120, both of 



LATHES AND LATHE WORK 



201 



which are in the set. Another difficulty now arises. These 
two wheels will not gear, so an intermediate wheel must be 
added. This intermediate wheel may be of any suitable 
size (an 80 wheel being generally taken), and in the calcu- 
lations must be reckoned as both a driving and a driven wheel, 
thus maintaining the ratio 

40 X 40 40 80 40 4 



^^ X 



or 



X 120 "120 "" 80 120 120 12 

This train of wheels, shown at Fig. 190, having only one 
intermediate wheel, is called an " open train. "" 

As a further example, assume twenty-four threads to cut on 
a lathe with a lead-screw^ of two threads per inch. 

2 20 20 X 80 20 x 40 
24"240"'80x240~80xl20 

As 120 is the largest wheel, it becomes necessary to add two 
intermediate wheels, as shown at Fig. 191, and when so placed 
they are called a " compound train. ^^ 




Open Train of Wheels. Compound Train of Wheels 

Fig. 190. Fig. 191. 

To prove the wheels, multiply all the driving wheels 
together, and all the driven wheels, then divide one into the 
other. The product should be the same as the ratio originally 
commenced with, or threads to be cut and threads on lead- 
screw per inch. 



202 METAL-WORK 

Taking Example No. 1: 

3-2=^3 = ratio. 

The drivers are 40, 80, and driven wheels 80, 120. 
40x80-3,200 80x120=9,600 

9,600^3,200- i 

No. 2: 

2 1 20, 40 are drivers; 

24^ 12 80, 120 are driven wheels. 

20x 40= 800 80 x 120= 9,600 

9,600^800= -t 

When cutting a screw in the lathe, it is necessary to go over 
the work several times, working slightly deeper each time until 
the thread is fully formed. Care must be exercised so that 
the tool follows the same path each time. This works out 
automatically when the threads per inch to be cut can be 
exactly divided by the threads per inch on the lead-screw; but 
in cases where there is a remainder on dividing, care must be 
taken, or the tool may be brought on the top of the thread 
instead of into the groove. To avoid this occurring, place a 
chalk mark on the catch plate and the top of the lead-screw 
when the lead-screw nut just engages. At each restart the 
nut must only be allowed to engage when these two marks 
coincide. When arranging a train of wheels for screw-cutting 
right-hand threads, the lead-screw must revolve in the same 
direction as the mandril, but for left-hand threads in the 
opposite direction. 

When the lathe is foot-driven the power is transmitted 
through the treadle, but if driven by motor or engine power 
it is transmitted from the main shafting by means of a counter- 
shaft, as shown in Fig. 192. This is fitted with a pair of 
wheels (one fast and one loose) and a striking gear, whereby 
the belt can be made to run on either pulley, thus starting or 
stopping the machine as required. 



LATHES AND LATHE WORK 



203 



Testing and Care of 
Lathe. — In order to pro- 
duce true and accurate 
work, a lathe must be 
well made and kept in 
good condition. Many 
lathes are placed on the 
market without suffi- 
cient regard to the truth 
of the main parts or the 
perfect coincidence of 
the details. The com- 
ponent parts of a perfect 
machine are indepen- 
dently accurate, and 
these, when adjusted, 
should be in perfect 
coincidence with each 
other. A few of the 
more common defects 
to be looked for in 
selecting a lathe are — 

1. Bed out of Truth. 
— This fault is not com- 
mon, but when it does 
occur is generally due to 
one of two defects, or 
both. 

{a) Defective bolting 
clown during planing. 

(6) Distortion due to 
bolting to standards, 
without proper fittmg 
or care. 

To test the bed, lay a long straight-edge, metal if possible, 
across each end of the bed at right angles to its length. A 







d5 

h-l 



204 METAL-WOUK 

very slight twist will be considerably magnified by the length 
of the straight-edges, and can be detected by the eye or by 
testing each straight-edge with a spirit-level. 

2. Headstocks not in Alignment. — First bring the loose 
headstock up, and try if the two centres come exactly into 
contact. Afterwards place the loose headstock at the extreme 
end of the bed, and test with a long thin straight-edge, which 
should be used so that the opposite edges of the straight-edge 
rest against opposite conical faces of the centre. Test on each 



Lathe Centre 




Str; 




ybte,^l 



Fig. 193. 

side, tox) and bottom. This will readily show (Fig. 193) if the 
centres are in alignment throughout the length of the bed. 

3. Non-Parallelism of the Fast and Loose Headstock Mandrils. 
— This defect can be detected by loosening the fast headstock, 
and fixing it on the bed to the right of the loose headstock. 
Now reverse the loose headstock, and test if its centre coincides 
with the centre of the thrust-pin. If these centres do coincide, 
the mandrils are parallel, and also of equal height above the 
bed at each end. 

4. Bad Fitting of the Loose Headstock Barrel. — The truth of 
the boring and the barrel can be best tested by callipers, and 
by takmg the barrel out, reversing it, and trying it in the hole. 

5. Looseness of Slide Best. — This can be quickly tested by 
gripping the tool-post and straining it in all directions. Any 
slackness in the rest gives rise to " knocks,"" which can be 
located by the sound. 



CHAPTER XIX 

EEP0USS]5 WORK, ENGRAVING, POLISHING, 
BRONZING, AND LACQUERING 

Repousse Work. — The term " repousse "" is a French word, 
and is applied to designs formed on sheet metal with punches 
and hammers. The design is first scribed on the material 
and punched to the required depth. The face of the material 
is then chased back, and the design finished off. 

Repousse work can be applied to many models in the 
handicraft-room, of which trays, vases, sconces, serviette- 
rings, teapot-stands, and photo-frames, are typical examples. 
Figs. 194 and 195 show examples as applied to the ash-tray 
and photo-frame. The most suitable metals for this work are 
copper, brass, aluminium, and pewter, but cold-rolled sheet 
copper of about 30 to 32 gauge will be found to give the 
best results in the handicraft-room. 

In the process of repousse working, the metal is first 
cemented to a wooden block by a mixture of equal parts of 
Burgundy pitch and plaster of Paris. This cement is pre- 
pared by melting the pitch in an iron pan, and adding the 
plaster while the pitch is being stirred, so as to thoroughly 
unite the two materials. The addition of a little Russian 
tallow and resin improves the mixture by making it less brittle, 
and consequently holding the metal better. When prepared, 
the mixture is poured over the wooden block (which is im- 
proved by being formed into a shallow box J mch deep), and 
the metal to be worked pressed firmly upon it. It is now 
allowed to cool, after which it is ready for use. 

205 



206 



METAL-WORK 



The design is either drawn upon the metal or transferred by 
the aid of carbon-paper, and the outline worked mto the metal 
by means of steel punches called " tracers/' These tracers 
are practically small flat chisels, the sharp edges of which 
vary in length, and have been blunted or rounded upon an 




Fig. 194. — IIepouss:^ Ash-Tray. 



oilstone. Tracers should be held with the thumb and first 
finger, the second finger being employed in steadying the 
tool, and the third lying on the metal for the purpose of 
guidmg. The hammer used is shown at Fig. 61, and should 
be used lightly and quickly, a rise of about an inch and 120 
blows per mmute giving the best results. If the work is 



REPOUSSfi WORK 



207 



punched too fiercely, the metal, being thin, is Uable to shear or 
cut. 

Many pleasing designs can be obtained by tracing only, 
but the bolder designs obtained by subsequent bossing (or 




Fig. 195.— Repousse Photo-Frame. 

embossing) are more effective. To carry out this operation, 
the metal is removed from the pitch-block after tracmg, and 
hammered or punched on the reverse side to form the neces- 
sary relief ; this operation may be carried out upon the same 



208 METAL-WORK 

pitch-block by cementing it down again with the back of the 
exercise uppermost. A pad of modelling wax^ a block of soft 
wood, or a bag filled with sand, may also be used for this part 
of the work. Boxwood punches are often used for the bolder 
modelling, and steel punches always for the finer details. 

After embossing, the metal should be again reversed and 
fixed to the pitch-block, whilst the design is finally worked up 
with suitable punches. If it is desired, the background may 
at this stage be " matted.'" The matting punch has usually 
a square face cut with diagonal or square Imes, which produce 
a series of evenly-spaced dots. Care must be taken not to 
punch any portion of the surface more than once, and to 
strike sharp blows of even force. When finally removed from 
the block, the metal is usually bent out of shaj)e, and may be 
flattened by placing it upon a metal block, and carefully 
striking it with a mallet. During the process of repousse 
working, the sheet metal, as has been noted, has to be removed 
and refixed, and may also require frequent annealing to aid 
the working, which is performed by heating with a gas blow- 
pipe, Bunsen burner, or spirit-lamp. 

Engraving. — This is one, if not the oldest, of the decorative 
arts. Numerous examples are to be seen in the Egyptian 
Section at the British Museum, and there are records of "four 
engraved silver vases "" being destroyed at the burning of the 
Temple of Diana at Ephesus in the year 356 B.C. The opera- 
tion is simple, and yet the result is very effective. Simple 
engraving on soft metals, such as aluminium and zinc, provides 
good practice, and many models in these metals made in the 
handicraft-room can be improved by a little decoration in this 
manner. Fig. 196 shows an example in aluminium suitable 
for the bottom of a tray, and most of the models mentioned 
as suitable for repousse working can also be embellished by a 
little engraving. 

The tools used vary considerably in sectional shape, but the 
" lozenge " graver (Fig. 197), "knife-edge'" graver (Fig. 198), 
and "round-nose"' graver (Fig. 199), will be found quite 



ENGRAVING 



209 

--1 




Fia. 196. — Engraved Tray Bottom. 

sufficient for handicraft purposes. When purchased^ gravers 
are as a rule too soft for immediate use, and must be hardened 
and tempered to a light straw colour, and afterwards 
" whetted up/' or sharpened, upon a fine oilstone. The 

14 



210 



METAL-WORK 



tools are fitted to a knob-shaped handle (Fig. 200), which is 
grasped in the palm of the right hand, while the graver is 
guided with the thumb and first finger of the left hand. 

The model or plate to be 
engraved is first cemented 
to a wooden block by a 
cement composed of Bur- 
gundy pitch 2 parts, resin 
Ij parts, beeswax IJ parts, 
and plaster of Paris 1 part. 
The ingredients are melted 
together in an iron pan, 
and well stirred to insure 
thorough mixing, after which 
the mixture is poured into 
a pail of cold water. A 
u) III ill iiiiiiiii I liiiiiiiii small quantity is then taken, 

broken into a fine powder, 
and spread upon the block. 



Fig. 197. 




n3 

U1 

^ 01 

Pig. 199. 




Fig. 200. 



The metal is placed upon this powder, heated with a Bunsen 
burner or blow^pipe until the cement melts, and allowed to 
cool, after which^the block should be firmly gripped in a vice. 
The design is now accurately drawn on the metal with a pencil. 



POLISHING 211 

and carefully cut with the gravers. Extra prominence may 
be given to the design by graving shading lines across the 
background. Monograms, initials, and school badges, can be 
produced by pupils after a little practice. 

Finishing and Polishing. — Finishing and polishing are opera- 
tions in metal-working too often left out of the handicraft- 
room, and as a consequence many examples of good work are 
not shown at their best. In other instances, by inattention 
to these items, which require considerable skill, good work is 
spoiled by removing sharp, clean edges, and leaving rounded 
ones in their place, thus injuring the more delicate detail. 
Finishing and polishing, as applied to the metal-worker, 
embraces all processes used for removing tool-marks and giving 
a smooth surface to finished models. The most common 
finishing method m the handicraft-room is carried out by the 
use of emery-cloth, grades 2 and 1 being used, in that order, 
and oiling the latter during the last few strokes. 

This gives a sufficiently fine surface for iron or steel, but 
with brass, copper, zinc, and aluminium, the process should 
be followed by rubbing with " Water of Ayr " stone to remove 
scratches, and with " blue "" stone and a leather " buff-stick " 
to add a high polish. This buff-stick consists of a strip of 
leather glued to a strip of wood. Work with uneven surfaces, 
such as repousse, is better treated by dilute acids. For brass- 
work, first dip the article into dilute nitric acid, then wash 
in running water, and rub with fine silver sand and sawdust in 
the order given. For copper, the object is washed in a bath 
of dilute sulphuric acid, and afterwards rubbed with fine 
silver sand; then washed in running water, rubbed with pumice- 
stone, and dried with sawdust. A dead, dull surface, called 
" dead-dipping,'" is obtained by first dipping the model in 
nitric acid, followed by washing in a bath composed of 1 ounce 
of cream of tartar to 1 gallon of water, and finally drying 
in fine sawdust. After " dead-dipping,'" a good effect can be 
produced by burnishing the high parts of repousse work. 

Burnishers are made of highly polished steel, and shaped to 



212 



METAL-WORK 



suit projections in the work. The model, when being bur- 
nished, should be lubricated with water, soap-suds, vinegar, or 
lemon-juice, the burnisher must press hard against the work 
and move backwards and forwards with a sliding motion. 
" Marbling "" on brass, copper, or aluminium, is done with a 
pointed slate-pencil and water, the pencil being moved in 
small circles, which should interlace in all directions. 

Bronzing. — Bronzing is a process by which brass and copper, 
by means of chemical baths or solutions, are made to assume 
various colours. Brass can be coloured through almost the 
whole of the spectrum scale, the composition of the baths 
being as follows : 



Colour, 



Orange 
Violet 

Moire 

Brown to deep red 

Pale to dark green 

Blue 

Steel grey 
Black 



Bath. 

(To 1 pint of water in each case 

add as under.) 



Remarks. 



Acetate of copper (1 ounce) 

Chloride of antimony 
(1 ounce) 

Copper sulphate (2 ounces) 

r Nitrate of iron (2 ounces) 
' Hyposulphite of soda 
1^ (2 ounces) 

Perchloride of iron 
(8 ounces) 



Hyposulphite of soda 
(1^ ounces) 

Muriate of arsenic (1 ounce) 

/Copper chloride (| ounce) 
(Nitrate of tin (J ounce) 



Must be used warm. 
Must be used warm. 

Must be used boiling. 

Acts slowly. Will give 
all shades of red. 



Use cold. If very deep 
green is required, 
heat the model after 
removing from the 
bath. 

Use lukewarm. 



Use cold. 

Use lukewarm. 



The method commonly adopted to obtain a dead black 
surface on brass is to brush the metal over with a solution of 
1 part nitrate of tin to 2 parts chloride of gold, dissolved in 



LACQUERING 



213 



a little water and mixed with an equal quantity of pure hydro- 
chloric acid. A slight excess of acid tends to mcrease the 
intensity of the black. 

In bronzing copper the baths are — 



Colour. 



Blue to black 



Dark brown 



Brown to black 
(through blue) 



Bath. 



Vinegar (1 ounce) 
Verdigris (1 ounce) 



Sal-ammoniac (^ 



ounce 



/Water (1 pint) 

\ Nitrate of iron (5 drachms) 

'Water (1 pint) 
Potassium sulphide or 
ammonium sulphide 
(1 ounce) 



Remarks. 



Dilute the solution with 
water until the solids 
aredissolved. Use hot. 

Use luke warm. 



Use cold. Make up fresh 
solutions as required. 



Lacquering. — Lacquering consists of coating with varnish 
(lacquer) metallic surfaces to prevent oxidization and conse- 
quent loss of colour. Two forms of lacquering are in common 
use, and are known as the " hot " and " cold "" methods. The 
cold method consists in applying the lacquer, without any 
previous preparation, evenly over the surface with a fine 
camel-hair brush, but, unless done by someone having a fair 
amount of experience, it gives a white streaky result, and does 
not endure for any great length of time. These faults practi- 
cally prohibit the use of cold lacquering m the handicraft- 
room. 

Hot lacquering will, however, be found to be well within the 
capabilities of the average pupil. The object to be coated is 
heated to a temperature which aUows it to be handled with 
care. This even temperature is best obtained by placing a 
sheet of thin iron across the top of the soldering stove and 
allowmg the flame to burn very low. The model is placed 
upon this sheet, and constantly turned to insure even heating. 
When the desired temperature is obtamed, a thin coat of 



214 



METAL-WORK 



lacquer must be quickly applied, and the object cooled off 
slowly upon the same iron plate by turning the gas off. This 
method of cooling insures the lacquer " setting " properly. 
A wash of methylated spirits before beginning the process 
heljos the lacquer to spread and lie evenly. Colourless lacquer 
is mostly used in the handicraft-room, but occasionally a 
lacquer with some definite colouring property may be re- 
quired. 

The following table gives the colour and composition of 
various lacquers : 



Colour. 


Composition. 


RemarTcs. 


Colourless 
Green 
Fine gold 

Deep gold 
Bronze 


( Methylated spirit (1 quart) 
\ Fine shellac (1^ ounces) 
I Gum sandarach (1 ounce) 

' Methylated spirit (1 quart) 

- Fine shellac (IJ ounces) 
( Turmeric {\\ ounces) 

r Methylated spirit (1 quart) 
J Fine shellac (2^ ounces) 
vRed Sanders {\ ounce) 

'Methylated spirit (1 quart) 
Shellac (4 ounces) 

- Turmeric (^ ounce) 
Gamboge {^ ounce) 
Dragon's-blood {\ ounce) 

'Methylated spirit (1 quart) 
Shellac [^ ounce) 

- Sandarach (| ounce) 
Gum acaroides {\ ounce) 

^Gamboge (^ ounce) 


Mix well, allow to stand 
for a week, strain, and 
bottle for use. 

Proceed as for colour- 
less. 

Grind the shellac and 
Sanders in a mortar, 
then dissolve in spirit. 
Strain before using. 

Dissolve shellac in spirit, 
then add the other in- 
gredients. Mix well, 
allow to stand for two 
days, then strain and 
bottle for use. 

Mix well and expose to a 
gentle heat for a few 
hours. When cold, 
strain and bottle for 
use. 



Lacquers should be kept in stone bottles and stored in a 
dark, cool place, as light tends to darken the colour, and 
heat causes the spirit to evaporate, thus rendering the mixture 
useless. 



PART III 

WORKROOM EQUIPMENT AND 
SCHEME OF WORK 



CHAPTER XX 

SPEEDS, FEEDS, AND POWER, REQUIRED FOR 
MACHINE TOOLS, SHAFTS, ETC. 

Speeds. — The proper speed and feed for machine tools is that 
which removes the greatest amount of metal without injury 
to the tool or machine. High speeds, by generating heat, 
tend to draw the temper from the tools, rendering them so 
soft that they quickly lose their cutting edge. On the other 
hand, should the speed be too slow the tendency is to cause 
chattering and breakage of the fine cutting edges of the tool; 
also the amount of work done in a given time is considerably 
reduced. 

The following tables show, approximately, the proper 
speeds for the various machines and tools in the handicraft- 
room : 



Operation. 


Material. 


Circumferential Velocity 
in Inches per Minute. 


Turning 


- 


Cast-steel 
Cast-iron 
Mild-steel 
Wrought -iron 
Brass 
, Copper 


150 
160 
200 
250 
300 
350 



Note.- -'For screw-cutting decrease 50 per cent., and for fine finishing 

increase 25 per cent. 

215 



!16 



WORKROOM EQUIPMENT 



Operatioyi. 


Material. 


Circumferential Velocity 
in Indies per Minute. 


Boring 


■ 


Cast -steel 
Cast-iron 
Mild-steel 
Wrought-iron 
Brass 
^ Copper 


100 
120 
150 
175 

225 
250 



Operation. 


Material. 


Periplierical Speed of Brill 
in Inches per Minute. 


Drilling 


^ 


" Cast -steel 

Cast-iron 

Mild-steel 

Wrought-iron 

Brass 

Copper 

Zinc 
I Aluminium 


170 
180 
200 
225 
300 
320 
320 
320 



Feeds.- 



Operation. ■ 


Measurement. 


Revolutions per Inch 
Feed. 


Turning and boring 
Drilling 


rUp to ^ inch diameter 
- From ^ to 1 inch diameter 
Slightly over 1 inch diameter 


40 to 60 
200 „ 250 
150 „ 200 
100 „ 120 



The pressure on the head of a drill (iii pounds) necessary 
to ]3roduce the proper cut equals the diameter of drill in 
inches x 1,500 . 

Hack-saws for hand or power should run at about forty 
strokes per minute. 

Grindstones should run at a circumferential velocity of 
about 800 feet per minute. 

Emery ivheels should run at a circumferential velocity of 
about 5,000 feet per minute. 



SPEED, FEED, AND POWER 217 

Polishing with emery-cloth and oil, not less than 750 feet 
per minute circumferential velocity. {Note. — The higher the 
speed, the better the polish.) 

Speed of Main Shafting : 120 to 150 revolutions per minute. 

Speed of Counter-Shafting : 150 to 250 revolutions per 
mmute. 

Power required to drive Shafting and Machine Tools. — Line 
and counter-shafting absorb about 25 per cent, of the energy 
transmitted to them ; or, for every 75 horse-power of useful 
work requhed the motor or engine must be capable of giving 
100 horse-power. 

The rule for finding the actual horse-power required to 
drive machines by belting is — 

— — = actual horse-power ; 

where C= circumference of fast and loose pulleys in feet, 
R = revolutions of counter-shafting per minute, 
IT = width of belt in inches, 
1,000= constant. 

Actual Horse-Power required to drive Machine Tools 
(from Tests taken at East Ham Technical College). 

Horse-Power. 

4J-inch centre screw-cutting lathe . • . . . . . . 0"33 

4-inch centre plain lathe . . . . . . . . . . 0*22 

G-inch stroke shaping-machine . . . » . . . . 0'17 

Small high-speed drilling-machine (drilling up to j inch 

diameter) . . . . . . . . . . . . . . 0*26 

Slow-speed drilling-machine (drilling up to f inch diameter) 0'32 
Emery -grinder with two 8-inch diameter wheels (running 

4,850 feet per minute) . . . . . . . . . . 0*56 

Grindstone, 36-inch diameter x 6-inch face (running 680 

feet per minute) . . . . . . . . . . . . 0-69 

Small fan for blowing two fires . . . . . . . . 0*29 

Power hack-saw, 10-inch blade . . . . . . . . 0'43 

Note. — The machines in each case were taking their maxi- 
mum load. 



218 WORKROOM EQUIPMENT 

RlJLES TO CALCULATE SpEED AND SiZE OF PULLEYS 

AND Shafts. 

1. To find the speed of a comiter-shaft, if the revolutions 
of the main shaft and pulleys are given : 

rev. of main shaft x diam. of main shaft pulley in inches 
diam. of counter-shaft pulley in inches 

Example. — What will be the speed of a counter-shaft with a 
12-inch pulley, driven by a 30-inch pulley revolving 180 revo- 
lutions per minute ? 

180 X 30 



12 



450 revolutions per minute. 



2. To find the size of a pulley to give a known speed, if the 
number of revolutions and size of pulley on the driving-shaft 
are given: 

diam. of driving-whee l in inches x rev. of d. -wheel per min. 

speed required 

Example. — What will be the diameter of a pulley to make 
a counter-shaft revolve 450 revolutions per minute if driven 
from a 30-inch pulley on a main shaft revolving 180 per 
minute ? 

180 X 30 



450 



= 12 -inch diameter. 



3. To find the size of a pulley for a main shaft, if the speed 
of the main and counter shafts and the diameter of pulley on 
the counter-shaft are given: 

diam. of c.-shaft pulley in inches x rev, of c. -shaft per min. 
rev. of main shaft per min. 

Example. — What will be the diameter of a pulley on a main 
shaft making 180 revolutions per minute required to drive a 
12-inch pulley on a counter-shaft at 450 revolutions per 
minute ? 

— " := 30-inch diameter of pulley. 
180 ^ '^ 



CHAPTER XXI 

STANDAED THREADS, BOLTS, AND GAUGES— SIZES 
AND PRICES OF MATERIAL 

Standard Threads. — A uniform system of screw-threads was 
first prepared by the late Sir Joseph Whitworth, and pub- 
lished by him in 1841. This system is now universally 
adopted in Britain, and is known as the " Whitworth " English 
Standard Thread. The form of the thread is a triangle, the 
two sides enclosing 55 degrees; the top and bottom of the 
thread are each rounded off one-sixth of the total height, thus 
reducing the depth of the thread to two -thirds the height of 
the full triangle (see Fig. 201). 

In America a different form of screw-thread is in general 
use. It is known as the " United States Standard/" " Sellers/' 
or " Franklin Institute " Thread, and was first introduced in 
1864. This form of thread is an equilateral triangle of 
60 degrees, with one-eighth of the total height of the triangle 
flattened top and bottom, in a line parallel to the axis of the 
thread, thus reducing the height to three-quarters of the 
height of the full triangle (see Fig. 201). 

The " Swiss "" Standard Thread, introduced in 1876, is 
much used in horological and electrical work and for small 
scientific instruments. The thread is triangular, the two 
sides enclosing an angle of 47 J degrees. The top of the thread 
is rounded off by a radius of one-sixth of the pitch, and the 
bottom is rounded by a radius of one-fifth of the pitch, thus 
giving a depth to the thread of slightly over three-fifths of the 
pitch. 

The British Association in 1881 tabulated a system of 

219 



220 WORKKOOM EQUIPMENT 

threads for " the small screws used iii telegraphic and other 
electric apparatus^ in clockwork^ and for analogous purposes/' 
This thready known as the " B.A./' is similar to the Swiss 
Standard^ but the romidmg is equal top and bottom, bemg 
two -elevenths of the pitch. 

The English standard for buttress threads is the same number 
of threads per inch as " Whitworth/' for square, and knuckle 
threads half the number. A bolt is usually screwed for a 
distance equal to 2*5 diameters. 

Nuts and Washers. — The English or Whitworth standard for 
nuts and washers was tabulated at the same time as the screw- 
threads, and is now adopted throughout the British Isles. 

Hexagonal or Square Nuts and Bolt-Heads. 

Bolt-head or nut across flats = IJ d. + ^ mch. 

„ „ thickness ==: 1 d. 

Diameter of washer = 2 d. 

Thickness ,, =| d. 

(d. = diameter of bolt.) 

Note. — Nuts, bolt-heads, washers, and spanners, are always 
specified by the diameter of the bolt they would fit — i.e., 

1-inch nut = If inches across flats. 

1-inch washer = 2 inches diameter by | inch thick. 

1-inch spanner = If inches across jaws. 

In addition to the vee forms of threads, three other forms 
of threads are in common use, mostly for transmitting motion 
— the square, buttress, and knuckle threads. The square 
thread is quite square in section. The buttress thread con- 
sists of a right-angled triangle with sides of equal length, thus 
enclosing an angle of 45 degrees. The knuckle thread is 
formed of semicircles of equal radii. In comparing these 
tln?eads with the vee or triangular form, it will be seen that 
the vee thread, having continuous metal at the bottom, is 
stronger than the square thread; but, owing to the pressure 
being taken in the vee thread on a face inclmed to the axis of 



STANDARD THREADS, BOLTS, AND GAUGES 221 

the screw, the tendency to twist the nut is considerably greater 
in the vee than the square thread. 

The buttress thread combines the advantage of both the vee 
and square tjrpe when the pressure is transmitted in one 
direction ; but should the direction of the pressure be reversed, 
the bursting action on the nut is greater than in the vee thread, 
on account of the larger angle on the slant side. The buttress 




Whitworth. 



Sellers u 




Swiss. 



British Association. 



hx^ 




Square. 


Knuckle. 




\--'4'5° / 


'%Af-lAJiA^ 


\ y 




Truncated Cone. Buttress. 

Fig. 201. — Screw-Threads. 



thread generates considerable friction, and is only used when 
the thread is subjected to rough and heavy usage. 

Lead-screws of lathes are sometimes cut with a thread 
known as the " truncated cone '" thread. This thread in 
section is the same as the section of a truncated cone. The 
advantage of this type of thread for this particular purpose is 
that the half -nut can be easily caught or dropped into the 
thread; and as the top of the nut thread is not allowed to 



222 



WORKROOM EQUIPMENT 

Table op Standard Screw-Thread Pitches. 



B.A. 

No. 


Diameter in 
Inches. 


Threads per Inch. 


Whitworthfor Gas 
and Water Pipes: 
Internal Diameter 












Whit worth. 


American. 


B.A. 


of Pipe. 


5 


1 2e 






43 


, 


4 
3 


142 

lOOo 


— 


— 


38-5 
34-8 


z 


2 
1 


2 09 
10 00 


— 


z 


31-4 

28-2 


— 




236 
IOTmT 

3V 


150 





25-4 







1 


60 


— ■ 


— • 


— 




A 


48 


— • 


— 


— 




1 

8 
6 
3 2 


40 
32 


— 


z 


28 






24 
20 


20 


— 


19 




Y 


18 
16 


18 
16 


— 


19 




1 

2 


14 

12 


14 
13 


— 


14 






12 
11 


12 
11 


— 


14 




H 


11 
10 


11 
10 


— 


14 


3 


1 


10 
9 


10 
9 


— 


14 




15 
1 


9 

8 


9 

8 


— 


11* 






7 
6 


7 
6 


— 


— 




If 

2 


5 
4* 


5 
4i 


— - 


■ — ■ 




2i 
3 


4 

3i 


4 

31 


, 


■ — • 




4 

5 


3 

2i 


3 


— 


. 




6 


2i 


n 


— ■ 


• • 



* All pipes above 1 inch internal diameter 11 threads per inch. 



STANDARD THREADS, BOLTS, AND GAUGES 223 

touch the bottom of the lead-screw thread when made, con- 
siderable wear is necessary before longitudinal slackness or 
shake is developed. 

The Pitch (sometimes called the " rise "") of screw-threads 
is one thread and its corresponding hollow, or, in other words, 
the longitudinal distance which a nut travels during one 
complete revolution of the screw. 

Fig. 201 shows the section of the various forms of screw- 
threads. 

Standard Gauges. — Sheet metal and wire are rolled to various 
thicknesses or diameters, which are specified by means of 
standard gauges. The Birmingham Wire Gauge formerly in 
use (B.W.G.) has been replaced since March 1, 1884, by the 
Standard Sheet (S.S. or S.S.G.) and Imperial Standard Wire 
(S.W.G. or I.S.W.G.) Gauges, which are used principally for 
iron, steel, brass, copper, and aluminium. 



Number. 


ThicTcness. 


Standard Sheet Gauge. 


Imperial Standard Wire Gauge. 


Decimals. 


Nearest 
Fractions. 


Decimals. 


Nea7-est 
Fractions. 


1 


0-3532 


u 


0-3U0 


5 

1^ 


2 


0-3147 


t\ 


0-276 


1 7 


3 


0-2804 


^ 


0-252 


i 


4 


0-2500 


i 


0-232 




5 


0-2225 




0-212 





6 


0-1981 


. — . 


0-192 





7 


0-1764 


3 
ITT 


0-176 





8 


0-1570 




0-160 


■ — ■ 


9 


0-1398 


— . 


0-144 





10 


0-1250 


i 


0-128 


i 


11 


0-1113 




0-116 




12 


0-0991 


■ — . 


0-104 


• . 


13 


0-0882 


3 
■5" 2" 


0-092 


• 


14 


0-0785 




0-080 


3 
'52 


15 


0-0699 





0-072 




16 


0-0625 


tV 


0-064 


^^ 


17 


0-0556 




0-056 




18 


0-0495 





0-048 


3 


19 


0-0440 


^ 


0-040 




20 


0-0392 




0-036 





21 


0-0349 





0-032 


1 
■5" 



224 



WORKROOM EQUIPMENT 



Number, 


Thickness. 


Standard Sheet Gauge. 


Imperial Standard Wire Gattge. 


Decimals. 


Nearest 
Fractions. 


Decimals. 


Nearest 
Fractions. 


22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 
40 


0-03125 

0-02782 

0-02476 

0-02704 

0-01961 

0-01745 

0-015625 

0-0139 

0-0123 

0-0110 

0-0098 

0-0087 

0-0077 

0-0069 

0-0061 

0-0054 

0-0048 

0-0043 

0-00386 


1 


0-028 

0-024 

0-022 

0-020 

0-018 

0-0164 

0-0148 

0-0136 

0-0124 

0-0116 

0-0108 

0-0100 

0-0092 

0-0084 

0-0076 

0-0068 

0-0060 

0-0052 

0-0048 


^\ 



The ordinary market sizes of sheets are — Iron or steel, 3 feet 
by 6 inches; brass, copper, ahuninium, 4 inches by 2 inches. 
Zinc is rolled in sheets 7 feet by 2 feet 3 uiches, 7 feet by 3 feet, 
and 8 feet by 3 feet. The thickness gauge for zinc is peculiar 
to the metal, and is known as the Zinc Gauge (Z.G.). 

Zmc Gauge. 



Number. 


Thickness. 


Number. 


Thickness. 


Nearest 
Decimals. 


Nearest 
Fractions, 


Nearest 
Decimals. 


Nearest 
Fractions. 


4 

5 

6 

7 

8 

9 

10 

11 

12 


0-008 
0-010 
0-012 
0-013 
0-014 
0-016 
0-019 
0-022 
0-025 


rh 


13 
14 
15 
16 
17 
18 
19 
20 
21 


0-028 
0-031 
0-035 
0-041 
0-050 
0-058 
0-061 
0-065 
0-072 





STANDARD THREADS, BOLTS, AND GAUGES 225 

Tinplate sheets are made of various thicknesses and sizes. 
The gauge used is peculiar to this material, and is known as 
Tinplate Gauge. The following table gives particulars of 
the standard sizes of tinplate: 



Gauge. 



IC. 

IX. 
DC. 
IXX. 

IXXX. 

DX. 

IXXXX. 

DXX. 

DXXX. 

DXXXX. 



Name. 



No. 1 Common 

One Cross 
Double Common 
Two Cross 

Three Cross 

Cross Double 

Four Cross 

Two Cross Double 
Three Cross Double 
Four Cross Double 



Size of 
Sheets in 
Inches. 



1 



124 
17 



12^ 
17' 
12J 
12J 
17' 



Nearest 

Thickness in 

Inches. 



0-012 

0-014 
0-OlG 
0-017 

0-018, 0-019 
0-020 
0-021 

0-025 

0-028 
0-032 



N'earest 

Standard Wire 

Gauge. 



30 

28 
27 
27 full 

26 
25 
25 full 

23 

22 
21 



Tinplate sheets 14 by 20 inches, of one or two cross thick- 
ness, are most suitable for use in the handicraft-room. 

15 



226 WORKROOM EQUIPMENT 



Stock Sizes of Material for Use in the Handicraft-Room. 

The following tables give the nsual stock sizes of metals. 
Material of almost any size and section can be obtamed by 
special order : 

Wrought-Iron and Mild -Steel. 

Round (diameter in inches) : 

h t\, h t\. h r\, h h h h h Ih li 14. 2, 21, 3. 
Square (length of side in inches) : 

h t\, h T%, h I'lT, h h h h h ih If. H. 2, 2i, 3. 

Rectangular (sizes in inches) : 

tVx i, f, h f, 1, li, li, If, 2, 2J, 21 2f, 3, H, and 4. 

3 V 1 3. JL 3 1 11 a„fi 2 
3^-^ 4» 8' 2' 4» ^' ^2' '*i^*-*^ ^* 

ix i, I, h h h h 1. li li 1|' 2, 2i, 2J, 2|, 3, 31, 4, 5. and 6. 

fVxi,f,i,|, 1, IJ, If, 2, 3,and4. 

Ixhh h h h h li, li, U, If, 2, 21, 3, 31, 4, 5, and 6. 

IB X 2» 4, ■'^, •■-•J:' "IIU J.2' 
3vl 5 3. 1 11 arir\ 11 

/^x4, f, 1, 1-1, and IJ. 
^xf, 1,11, u, If, and 2. 

Iron and steel sheets are stocked in all thicknesses of the 
standard sheet gauge. Usual size, 6 feet by 3 feet. 

Iron and steel wire, plain, tinned, or coppered, can be 
obtained in any size of the standard wire gauge. 

Cast-Steel. 

Round (diameter in inches): |, ^%, I, -^-^, f, ^, |, f, |, 1. 
Square (length of side in inches): J, |, ^, f, f, |, 1. 
Hexagonal (distance across fiats in inches): |-, J, |, ^, f, f, 1. 
Octagonal (distance across flats in inches): J, f, ^, f, f, 1. 
Rectangular (sizes in inches): yVx i, f, and 1. 

ixj, I, 1, IJ, and 2. 

Jx ^, f, and 1. 



STOCK SIZES OF MATERIAL 227 

Brass. 

Sheets 4 by 2 feet are obtainable in all sizes of the standard 
sheet gauge. 

Round (diameter in inches): |, x\, J, i%, |, |, f, 1, 1^, IJ, and 2. 
Square (length of side in inches): ^-, f, |, f, f, and 1. 
Rectangular (sizes in inches): yVxi? f» 1» ^h ^^^ ^i- 

ixi I, 1, IJ, U, lf,2, 3,4, and6. 

Copper. 

Sheets 4 by 2 feet are stocked in all gauges of the standard 
sheet gauge. 

Round (diameter in inches) : ^, fV, I, f , ^, f , f , 1. 
Square (length of side in inches) : J, f , ^, f , 1. 
Rectangular (sizes in inches) : tV X J, f , and 1. 

ix|, f, 1, 11, and 11 

Brass and copper wire can be obtained in any size of the 
standard wire gauge. 

All sections of brass and copper can be obtained " hard '' 
or " soft "' rolled. 

Zmc. 

Sheets 7 feet by 2 feet 8 inches, 7 feet by 3 feet, and 8 feet 
by 3 feet, are obtainable in all sizes of the zinc gauge. 

Round (diameter in inches) : j, f , ^, f , 1. 

Square and rectangular zinc can only be obtained by special 
order. 

Aluminium. 

Sheets 4 by 2 feet and 6 by 4 feet can be obtained in all 
sizes of the standard sheet gauge. 

Round (diameter in inches): ^^, f, fV, |, f, f, 1. 

Aluminium wire is rolled in almost all the sizes of the 
standard wire gauge. 

Square and rectangular aluminium can only be obtained by 
special order. 



228 



WORKROOM EQUIPMENT 



Weight and Price of Metal. 



Metal. 


Weight of 
1 Cubic Foot 
in Founds. 


Metal. 


Weight of 
1 C^ibic Foot 
in Founds. 


Copper 

Brass 

Steel 

Wrought -iron 


549 
505 

489 

480 


Cast-iron 

Zinc 

Aluminium . . 


450 
449 
160 



Sheet Copper. — Sheets 4 by 2 feet. Standard sheet gauge: 

20 = 1*625 pounds per foot super. 

22 = 1-25 „ 

24 = 1-0 

26=0-75 pound 

28=0-5 

30=0-375 „ 

Brass, about \^ the weight of copper. 

Akiminium 1 foot square by 1 inch thick weighs 
14-2 pounds. 
- Iron and Steel. — Figures for obtaining approximate weight : 

Sectional area in square inches x 3-3= pounds per foot 

run. 
Cubic inches x 0-282= pounds. 
Round metal diameter x diameter x 2-62 pounds per 

foot run. 

Cast-Iron. — Averages about 2d. per pound for small plain 
castings, but increases if the pattern be cored or complicated. 

WrougJit-Iron and Mild-Steel. — Average sizes, 10s. per 
hundredweight. Small sizes increase to 25 per cent.; large 
sizes decrease to 10 per cent. 

Cast-Steel. — Average size and quality, 6d. per pound; 
better quality and smaller sizes, up to Is. per pound. 

Brass. — Sheets, round, squares, and rectangles, average 
size, 9d. per pound. Very thin sheets and small rods average 
Is. per pomid. 



PRICES OF MATERIAL 229 

Copper. — -Sheets, round, square, and rectangles, average 
size. Is. per pound. Very thin sheets and small rods, about 
Is. 4d. per pound. 

Zinc. — Average sizes, 4d. per pound; thin sheets, 6d. per 
pound. 

Aluminium. — Average sizes. Is. 6d. per pound. 

Lead in Pigs. — ^ About 25s. per hundredweight. 

Solder. — From Is. to Is. 6d. per pound. 

Rivets. — Brass, Is. per pound; mild-steel, 4d. per pound. 



CHAPTER XXII 

MOTIVE POWEK: STEAM-ENGINES, GAS AND OTHER 
ENGINES, AND ELECTRIC MOTORS 

Where the conditions are favourable, the above three forms 
of power are available for use in the handicraft-room. The 
steam-engine, while having the advantage of being self-con- 
tained, owing to the amount of time occupied in raismg 
steam and the contmual attention necessary to mamtain 
water and steam pressure in the boiler, is practically unfitted 
for use as a source of power for the handicraft-room. 

Gas and oil engines are very suitable for driving the machines 
in the handicraft-room, and where electric current is not 
available may be said to be the ideal power. The only great 
disadvantage of this form of power as compared with electricity 
is first cost and the trouble and time occupied in startmg. 
Gas and oil engines are identical in principle, but where town 
gas is available the gas-engine is cheaper in rmming, and 
more convenient in use, than the oil-motor. 

The electric motor, where available, is the ideal source of 
power for the handicraft-room. It is cheajo in first cost, 
occupies little space, is readily started and stopped, and 
requires little attention when running. In motion it causes 
neither smell, smoke, nor noise, and when not running, there 
is no waste of energy. 

In first cost the electric motor is considerably cheaper than 
either of the other forms of power, as the following figures show : 

5 horse-power engine and boiler, fixed complete, average price . . 60 

5 „ gas or oil engine „ ,, ,, ,, • • 35 

6 „ electric motor ,, ,, ,, ,, • • 25 

230 



MOTIVE POWER 231 

While the running cost works out at about — 

Per Hour. 
5 horse-power steam-engine . . . . . . . . 6d. 

5 „ gas or oil engine . . . . . . . . 5d. 

5 ;,, electric motor . . . . . . . . 3d. 

It will thus be seen that, in addition to its other advantages, 
the electric motor is cheaper as a source of small power, both 
in prime and running costs, than either steam or gas engines. 
It should be noted that the figures quoted only apply to small 
powers. In the case of large powers, say engines of 50 to 
100 horse-power, the steam-engine is cheaper than any of its 
rivals. 

The Steam-Engine. — Steam-engmes are of many types, but 
all depend on the same general principles. Fig. 202 is a dia- 
gram of the simplest and most common form of a small re- 
ciprocating engine. The steam is admitted from the steam- 
pipe into the steam-chest, and then, by means of the slide 
valve, through ports or steam- ways to the cylmder. The 
slide valve operates so that the steam presses first on one and 
then on the other side of the piston. The pressure on the 
piston forces it along the cylinder, and the motion thus ob- 
tained is transmitted through the piston and connecting rods 
to the crank pin, where it causes the crank to revolve. This 
type is called a "double-action reciprocating engine'' — "double- 
action " because the piston is acted on alternately backwards 
and forwards, which action is known as " reciprocation,'' and 
hence the term " reciprocating." Fig. 203 shows an enlarged 
view of the cylinder, piston, steam-chest, and slide valve. The 
cylinder is closed at each end by covers, through one of which 
passes the piston-rod, which is kept steam-tight by means 
of the stuffing-box and gland. The stuffing-box is filled with 
yarn or packing, which is pressed tight against the rod by 
screwing in the gland. The steam enters the steam-chest by 
the steam -pipe, and is controlled by the slide valve, otherwise 
it would enter the cylinder and press on both sides of piston. 
The slide valve is hollow and of sufficient length to cover both 
steam-ports, between which is the exhaust passage for the 



232 



WORKROOM EQUIPMENT 




Enlargement of Eccentric 
showing Throw at X 



f» 



Steam Pipe I | 

Valve Rod Guide 




1 II 1 1 II Fly Wheel ''i l| 






II 






J — 


|ii.;l| 







Eccentric Rod J|J_— Eccentric • 



^ Cross Head Connecting 
r\-^ — — f\/B.od [7^ 



3°° : '°]4i 



!l 



j J —Crank Shaft 



Guide Bar 



Crank 
Pin 



3 



Main Bearing 



[CTa 







Fig. 202.^ — Diagram of Steam-Engine. 



Stuffing Box and 
Gland 




Fig. 203. 



MOTIVE POWER 233 

release of the used steam. The figure shows the left steam - 
port just open, which allows the steam to enter and press the 
piston forward. As the piston moves, the valve moves in 
the same direction until the port is fully micovered, when it 
moves back again until the port is just covered. At this point 
the piston has completed its forward stroke, when the valve, 
still moving backward, opens the right-hand port, allowing the 
steam to enter this side and press the piston backward. As 
the right-hand port opens, the left-hand port, by means of the 
recess in the slide valve, comes into communication with the 
exhaust port, thus allowing the used steam to escape. This 
backward and forward movement of the piston and action of 
the slide valve is, of course, continuous as long as steam is 
admitted to the steam -chest. 

The slide valve is operated by means of an eccentric (see 
Fig. 202), which consists of a disc keyed to the crank shaft, 
with its centre out of centre with the crank shaft. This eccen- 
tricity is termed the " throw "" of the eccentric, and must equal 
half the distance that the slide valve is required to travel. 

The Gas-Engine and Oil-Motor. — These types of prime 
movers are known as " internal combustion engines. "" With the 
steam-engine the fuel does not come into actual contact with the 
engine, but with gas and oil engines the fuel is brought into 
actual contact; in fact, combustion takes place in the engine 
cylinder, and this fact gives rise to the term " internal com- 
bustion engine. "" Coal gas, alcohol and petrol, and mineral 
oils, such as petroleum, are composed of hydrogen and carbon, 
and are known as " hydrocarbons. "" When any of these 
become mixed with atmospheric air the mixture becomes 
highly explosive. Gas-engines, oil-engines, and petrol-motors, 
are identical in general principle. The cylinder is fitted with 
valves which control the supply of fuel and air, and allow the 
escape of the waste products after combustion. These valves 
operate m given order, the whole series, which occupies four 
piston strokes, being known as the " Otto "' cycle of operations, 
after Dr. Otto, who, in about 1876, first proposed this arrange- 



234 



WORKROOM EQUIPMENT 



ment. Fig. 204 shows the operation of the valves during the 
" Otto " cycle of operations. 



Gas & AirA 
Inlet. 




Fig. 204. — Operation of Valves during Otto Cycle. 



Stroke A . — The piston moves outwards^ and the gas and air 
valves open, which admit the explosive mixture to the cylinder. 

Stroke B. — The piston moves inward and compresses the 
explosive mixture. At the end of the stroke the mixture is 



MOTIVE POWER 



235 



ignited (in gas and stationary oil engines by red-hot tube, and 
in petrol-motors by an electric sparking-plug) . 

Stroke G. — The expansion of the exploded mixture blows the 
piston outward. 



Water 
jacket 




Sparking 
^ Plug 



Fig. 205. — Section through Gas or Petrol 
Engine. 



Stroke 7).-— The momentum of the fly-wheel carries the piston 
backwards, driving out the burnt gases when the exhaust 
valve opens. 

The four strokes of the cycle are known as— 

A. "Intake'': gas and air taken into cylinder. 

B. " Compression " : mixture compressed. 



236 WORKROOM EQUIPMENT 

0. "Explosion"': mixture explodes, driving out piston; 
this is sometimes called the " working "" stroke. 

D. "Scavenger"": incoming piston drives out products of 
combustion. 

It will now be seen that the energy imparted to the piston 
during one stroke has to serve for the whole cycle of 
operations. This distribution is effected by fitting a heavy 
fly-wheel to the crank shaft, which carries the engine over 
the dead part of the cycle. Fig. 205 shows a section through 
a complete engine of the vertical type. 

Valves. — The valves of internal combustion engines have to 
be operated so that one complete cycle is carried out during 
two revolutions of the engine. This is effected by operating 
the valve shaft by a cog-wheel, which is driven by a second 
cog-wheel on the crank shaft, which has half the number of 
teeth of the valve shaft cog-wheel; owing to this arrangement 
the valve shaft is known as the " half -speed "" or " two-to-one "" 
shaft. The valves are usually of the mushroom type, being 
circular discs mounted on rods called " stems." The intake 
valve may be operated from the valve shaft, when it is said 
to be " mechanically operated,"" or it may be automatically 
opened by the suction action of the piston during the first 
stroke of the cycle, being kept on its seat at other times by a 
spring. In this case the valve is said to be " automatic."" 

Cylinder. — At the moment of explosion the internal cylinder 
temperature rises to about 3,600° F. Owing to this great 
increase in temperature, arrangements must be made whereby 
the cylinder can be kept cool; this is usually effected by fitting 
the cyhnder with a water-jacket through which water is circu- 
lated either by natural flow or by a circulating pump. Small 
engines are sometimes air-cooled by means of circular flanges, 
thus increasing the area presented to the air ; but the whole 
efficiency of this arrangement depends on the velocity of the 
surrounding air, so that, while air-cooled engines are suitable 
for motor-bicycles, they cannot be said to give satisfaction 
when used for stationary purposes. 



MOTIVE POWER 237 

In the case of oil and petrol motors the fuel must be turned 
into a gaseous state before entering the cylinder ; this is effected 
by means of a carburettor, of which there is a great varietj^ 
The principle of all carburettors is that the suction action of 
the piston draws a quantity of oil or petrol through a fine jet, 
and converts it into a very fine spray, which, mixed with a 
due quantity of air, becomes a highly explosive gas. 

The Electric Motor. — The action of the electric motor de- 
pends upon certain fixed laws of electricity and magnetism. 
If these laws are thoroughly understood, the action of the 
electric motor can be readily demonstrated. The following are 
the laws of electricity and magnetism which govern the 
motor : 

1. Magnets are of two forms — permanent and temporary. 
Hard steel when magnetized retains its magnetism, forming 
a permanent magnet, but soft iron can only be formed into a 
temporary magnet, as it loses all its magnetism on withdrawing 
the magnetizing force. 

2. If an insulated wire be wound round a bar of iron or steel, 
and an electric current passed through the wire, the bar be- 
comes magnetic. (The attractive force of the bar depends on 
the strength of the current and number of turns in the wire.) 

3. Magnetized bars, if hung freely on a pivot, immediately 
come to rest, pointing north and south. (These ends are 
called the " poles '" of the magnet, and are known as " north " 
or " south,"' as the case may be.) If the north pole of a magnet 
be brought into proximity with the south pole of another 
magnet, they immediately attract each other; but should two 
north poles or two south poles be brought close together, they 
at once repel each other. From these facts the following 
law has been established : Unlike poles are mutually attractive, 
and like poles mutually repellent. 

The polarity of electro -magnets depends on the direction in 
which the current flows in the encircling wire. For instance, 
let it be supposed that a bar of iron is wound clockwise with 
insulated wire, and the current enters from the left-hand side. 



238 



WORKROOM EQUIPMENT 



then the right end of the bar is its north pole ; when the current 

is reversed, entering from the right, the left end of the bar 

becomes the north pole. 

The essential parts of an electric motor are — 

1. The field magnet, which is continuously magnetized in 

the same polarity during the running of the motor. 




Fig. 206. — Diagrammatic Elevation of 
Electric Motor. 



2. The armature, in which the polarity is continually being 
changed. 

3. The commutator, by which the direction of the current 
in the armature is reversed, thus changing its polarity. 

Fig. 206 shows the diagrammatic elevation of an electric 
motor. It will be seen that the winding of the field magnet is 
continuous, thus magnetizing it with north and south poles at 
each end. 



MOTIVE POWER 



239 



The armature consists of a number of thin iron plates, which 
is secured to the shaft and wound with insulated wire, the ends 
of which are connected to the two strips of the commutator. 
Fig. 207 shows the commutator, which is a ring split longi- 
tudinally into two portions, against which the brushes that 
convey the current press for half a revolution. These remain 
respectively in contact with the same segments of the con> 
mutator, and the current flows in the armature in, say, a 
right-handed direction ; but during the next half-revolution 




\ 



Fig. 207. — Commutator and Armature of Electric Motor. 



the segments of the commutator that are in contact with 
each brush are exchanged, so that the direction in which 
the current flows in the armature is continuously being 
reversed. 

The action of the motor is effected by passing a current 
through the field magnet and armature windings, Avhich 
magnetizes the poles. Assume the armature to be at right 
angles to the faces of the field magnet, then, when a current 
passes through the armature, its north and south faces tend 
to seek the contrary faces of the field magnet. When the 



240 WORKROOM EQUIPMENT 

point is reached, the commutator reverses the direction of the 
current in the armature, thus reversing its polarity, and a 
further half -revolution of the armature occurs, then another 
reversal of current and polarity, and so on, as long as the 
current flows. It will now be seen that the action of the 
electric motor is simply a question of repulsion and attraction 
of like and unlike magnetic poles. 

The sketches Figs. 206 and 207 show a simple bipolar 
magnet and armature. Working motors generally have four, 
six, or more field magnets set inside a casting. The armature 
is also made with many faces, and corresponding segments in 
the commutator. 



CHAPTER XXIII 

EQUIPMENT OF THE HANDICEAFT-ROOM 

A SINGLE metal-work handicraft-room is usually equipped 
for sixteen to eighteen boys under one instructor^ and a double 
room for thirty- two to thirty-six boys under two instructors. 
The Board of Education Code allows twenty boys to be in- 
structed under each teacher; but^ considering the more in- 
tricate nature of the equipment, experience has now almost 
levelled the number to sixteen. The general arrangement of 
the room depends largely upon the equipment to be provided. 
The ground-plan of a typical London room is shown at Fig. 208, 
and of a North-Country room at Fig. 209. 

Perhaps the most important factor in the planning a room is 
the position of the windows and flues, the former regulating the 
position of such items as lathes, drilling, shearing and punch- 
ing machines, which require very good light, and the latter 
the position of forges and anvils. The floor under and sur- 
rounding the forges should be of concrete, and the remamder 
of wood blocks. If it is not convenient to concrete the required 
portion, the wood should be covered by y^-inch chequered 
plates, such as are often used for engine-room floors. About 
3 feet 6 mches of bench run per pupil is required, with a 
drawer or cupboard under each if possible, and the portion 
of the bench set apart for soldering should be covered with 
sheet iron or lead to protect the woodwork from the action of 
the acids used as fluxes. A bench may be provided for braz- 
ing if sufficient space is available, or this operation may be 
conveniently carried out on the forge hearth. In either case 

241 16 



U2 



METAL-WORK 



9 

to 

o 

GO 



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o 
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o 

o 

o 
o 
:^ 

&:J 
o 
o 




EQUIPMENT OF THE HANDICRAFT-ROOM 243 




Bench 



+- 



V 



Vises - 



Screw Cutting Shearing 
Plain Lathe Lathe Machine 

A i 



Punch 
Bear 




S^-.O' 



Grinder 



26:0- 



Vises 



To Woodwork 
Shop 



K5.<?- 



, /Drilling 
^'^1 Machine 



-+ 

Bench, 



•+ ' 



a- 5' 




244 



METAL-WORK 



a 



J-inch gas-pipe provided with a " full way '' tap must Le 



near. 



Each pupil should be provided with a rack, similar to 
Eig. 210, m which to keep his tools; other tools forming part 
of the general equipment should be kept in racks fixed to the 
wall, in convenient parts of the room. 

The following is a list of tools necessary for a room to accom- 
modate sixteen or eighteen pupils, with approximate costs : 



For Each Pupil. 



One vice, 3| to 4 inch jaw 
One bench hammer, f pound 
One 12-inch flat bastard file 
One 10-inch ,, ,, 

One 10 -inch flat smooth file 
One 3-inch try-square 
One 12-inch steel rule 
One pair of 5-inch steel dividers 
One centre-punch . . 
One steel scriber . . 
One flat chisel 
One cross-cut chisel 



£ 


6". 


d. 


1 





















3 















2 























6 








3 








1 








H 



6 



Machine Tools and Appliances. 
One 4 to 4J inch screw-cutting lathe 



■■\ 



One 3 -inch n on -screw-cutting lathe 



One drilling machine to drill up to |-inch diameter 

Two forges with 2x2 feet hearths . . each 

One shearing machine to shear up to ^ inch 
One punching machine to punch up to |- inch . . 

Note. — A combined shearing and launching 
machine is a little cheaper than separate 
machines. 

One grindstone or emery grinder „ ^ 



£ 


s. 


d. 


16 




to 





30 








10 



to 





12 








5 




to 





7 








5 








2 


10 





2 









1 



EQUIPMENT OF THE HANDICRAFT-ROOM 245 



General Bench Tools. 

Six dozen assorted files .. «. .. each 
One scribing block (6-incli pillar) 
One pair small vee blocks, 1^ X 1 ^ inches 
One surface plate, 10 X 8 inches . . 
Two hack-saw frames (adjustable), G to 10 
inches . . . . . . . . . . each 

Six dozen hack-saw blades, 8, 9, 10 inches, dozen 
Three 4-inch inside callipers . . . . each 

Three 4-inch outside ,, . . . . ,, 

One set stocks, dies, and taps, J to J by iV inch 

One set stocks, dies, and taps, xV to i ^7 ^V i'^ch 

One set twist drills, -^^ to |- by ^V inch . . set 

Three each, extra twist drills, \, -j\, fV inch, each 

One set of spanners, J to 1 x yV inch . . set 

One small piercing saw frame 

Six dozen piercing saw blades 

One chipping block (cast-iron) 12 x 8 X 3 

Two engineer's oil-cans, ^ pint 

One hand-vice, 4 inches . . 

Three diamond-point chisels 

Three half-round chisels . . 

One centering square 

One bevel gauge 

One tapping gauge 

One wire gauge 

One depth gauge . . 

One pair 10-inch wing compasses 

Two pair jenny callipers . . 

One set of punches, letters and figures 

Two rivet setts 

One set repousse tools 

One adjustable spanner . . 

One protractor 

One square reamer 



. dozen 
inches 
each 



each 



£ s. d, 
10 
7 







1 
3 











14 

4 

2 

8 

8 

1 10 
10 0] 
4 6 
3 
3 
2 
6 
8 
2 
2 
8 
8 
10 
4 

3 


1 
10 

1 

10 

1 

10 

3 6 

2 6 

8 



246 



METAL-WORK 



Tinjjlate WorJcing Tools. 



One double soldering stove 



each 



Two straight soldering bits, 8 oz. 

One hatchet soldering bits, 8 oz. . . 

One bick iron, 15 pounds weight. . 

1 funnel stake, 7 ,, ,, 

One hatchet stake, 10 pounds weight 

1 half-moon stake, 7 pounds weight 

One flat round horse-head 

One creasing hammer 

One pair Scotch shears, 4-inch blade 

Two pair tinman's snips, 2^ -inch blade 

,, ,, ,, ,, 2-inch blade .. ,, 

One ,, ,, ,, 2 -inch curved blade.. 

Two flat pliers, 6 inches . . . . . . each 

Three round-nose pliers, 3, 4, and 5 inches each 

One pair wire-cutting pliers, 5 inches 

Three small hide mallets . . 

Two small egg-ended boxwood mallets 

Three hollow punches, ^, J, f inch 

One lead block for punching 



each 



each 



set 



£ 


s. 


d. 


r^ 


3 


G 


J 

lo 


to 




10 








1 








1 


2 





15 








7 








9 








6 








3 








1 


6 





4 


6 





1 


8 





1 


3 





2 








1 


9 





1 


6 





1 


6 





1 


6 








9 





2 


6 





2 






Forge Tools. 

Three anvils, 100 pounds, with wood stands, 

per cwt. . . 
Two water-troughs, 24 x 12 x 12 inches . . each 
One small swage block, 12x I2x 4 inches 
,, hot sett 

,, ,, cold sett 

,, ,, fuller 
,, flatter 
Six pair small tongs . . . . . . each 

Two ladlefj, 5 'and 3 inches 



d. 



1 


10 








15 


6 





14 








2 


6 





2 


6 





2 


6 





2 


6 





1 


G 





1 


3 



EQUIPMENT OF THE HANDICRAFT-ROOM 247 



Machine and Lathe Tools. 

£ s. d. 

One set slide rest tools . . 10 

One 8-inch four-jaw independent chuck (for 

S.C. lathe) 2 10 

One i-inch drill chuck for small lathe . . . . 7 

One |-inch „ „ drilling machine . . 7 

One lathe tool-holder . . . . . . , . 7 G 

Two lathe carriers to take up to 1 inch . . each 14 

Two „ „ „ „ „ 1 inch „ 10 

One knurling tool . . . . . . . . . . 7 G 



248 



METAL-WORK 




M 
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o 
w 

Q 
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CHAPTER XXIV 

SCHEME OF WORK 

Method of Working. 

Model 1 — -Set-Square : Mild-Steel. — Cut out the necessary 
material, allowing about ^ inch all round for waste. File up 
one of the short sides to form 
the face edge, and from it 
(when finished) square up the 
second short side. Set off the 
required length on each of 
these sides, and join with a 
line dra\\Ti with the scriber; 
place a few centre - punch 
marks on the scribed line, 
and complete the model by ^ 
carefully filing to them. 




Model 1. 



-J 



16 



H%V 



24'- 




Model 2 — Name Plate : Brass. — Cut out the necessary 
material, allowing ~ inch all round for waste. File up one 

249 



250 



METAL-WORK 



long edge to form the face edge, and from it (when finished) 
square up one short side; then square off a line showing the 
correct length of the model, and file to line. The model will 
now be correct to length, with one long edge true. Place this 
long edge on the surface plate, and with the scribing block 
scribe a line to correct width and file to the line ; then set off, 
and drill the holes. Then nail the model to a block of wood, 
using the drilled holes for the nails, and file up the broad face, 
finishing by careful draw-filing and emery-cloth. The chamfer 
must now be accurately marked out on the surface plate with 
the scribing block, and carefully filed, using a small smooth file. 




Model. 3. 

Model 3 — Key Hooh : Aluminium. — ^The outline of the back 
plate should first be designed on paper. Cut out the necessary 
material, and before marking out the design the face of the 
metal should be neatly hammered with the ball pane of a 
small hammer, which improves the face and stiffens the plate. 
Having completed the hammering, carefully mark out the 



SCHEME OF WORK 



251 



required design on the back of the plate, so as not to scratch 
the outside of the model. Work out the design with the chisel 
and saw where possible; then finish with the smooth file and 
emery-cloth. Mark out and prepare the washer, and then 
bend up the hook from |^-inch diameter wire. Drill the neces- 
sary holes in the back plate and washer, and file the shoulder 
on the hook to fit; complete the model by lightly riveting the 
hook through the washer to the back plate. It is very advisable 
to use wood clamps'in the vice when working aluminium. 




Model 4. 



Model 4 — Match-Box Holder : Mild-Steel. — The design for 
the back plate should first be drawn on paper, then copied on 
to the steel sheet and worked out, finishing the edges by care- 
fully draw-filing and emery-cloth. The distance sliip ard 



252 



METAL-WORK 



holding plate should now be made to size ; then mark out and 
drill all the rivet holes. After drilling the holes, bend the 
holding plate, by gripping the small part in the vice, with the 
bending line coinciding with the top of the jaw, and lightly 
hammering the bend to a right angle. Finally get two snap- 
headed rivets of requisite length, place the heads in a riveting 
block or snap, and rivet the parts firmly together. 

Model 5 — Hinge : Brass. — Having designed the outline, cut 
out a strip of brass slightly wider than the finished size, and long 
enough to make both flaps of the model; then (using the 
hatchet stake) bend the ends to exactly fit the pin. If the 
brass is at all hard, it will be advisable to anneal it before 




Model 5. 

starting the bends. Cut the strip into two parts as required, 
and fit the bends. The waste on the tongue part can be re- 
moved by sawing, and from the groove by taking two saw-cuts, 
which can be joined by cuttmg with a small chisel. Having 
fitted the parts, secure the hinge by inserting the pin and 
lightly riveting both ends; file up to correct width, mark out 
and work up the outline of the design, afterwards draw-file the 
faces, and finish the model by polishing with fine emery-cloth. 

Model 6 — Callipers : Mild-Steel. — Cut out two strips of 
metal large enough to make the two legs of the model; then 
carefully mark out the shape on one strip, drill the rivet hole 
in both, and temporarily rivet the strips together, making sure 
that the marking is on the outside. Remove the waste metal 



SCHEME OF WORK 



253 



by drilling a series of holes, close together and just touching 
the lines, join the holes by chiselling, and file up to size; 
remove the temporary rivet, and draw-file both faces of each 




Model 6. 

piece. Obtain two bright washers and a short length of 
romid steel to form the rivet; assemble the parts, noting that 
the calliper points are placed correctly, then lightly rivet the 
model together. 

Note. — Owing to the extreme difficulty and time required, 
it is not usual for pupils to make calliper washers; bright 
washers are very cheap, and can be readily obtained. 

Model 1 — Pajper -Weight: Cast-iron. 
— The casting for the model should 
allow about |^ inch waste on all faces. 
Commence work by chipping and 
filing one broad face. The tendency 
to round this surface when filing is 
decreased if the strokes be taken 
alternately from corner to corner. 
From the prepared face, square and 
true one edge, from which the second 
edge must be obtained. Havmg 
thus produced one face and two 
edges mutually true and square to 
each other, mark out to correct size, 

using the scriber and try- square, the two remaining sides of 
the square; then chip and file to the scribed lines. Now place 




Model 7. 



254 



METAL-WORK 



the block, filed face down, on the surface plate, and with 
the scribing block scribe the correct height on each edge; 
chip and file to the lines thus obtamed, then mark out and 
file the chamfer. The centre of the block can now be got 
by joinmg the diagonals. Centre-pmich the exact spot, and 
drill a yg -inch diameter hole, the tapping of which comj)letes 
the model. To provide practice in scrapmg, the bottom face 
of the model may be scraped up to the surface plate. 

Model 8 — Fish Slice : Tinned Iron Wire and Tinplate. — 
Commence working this model by bending the ring to form 
the handle. This should be done around the bick iron, using 




Model 8. 

the hide mallet to prevent injury to the tinned surface of 
the wire. Having completed the handle, set off the correct 
distance to the commencement of the flattening for the joint. 
The flattening out is best done by placing the mark on the 
edge of the anvil, and giving the wire a few smart blows with 
the forge hammer, then carefully filing to size. Now obtain 
a piece of tinplate about J-inch larger than the finished size, 
scribe a line about |^-inch from one of the longer edges, and 
cut to it with the shears to form the face edge, from which 
the requisite sizes should be marked out and afterwards cut. 



SCHEME OF WORK 



255 



The position of the holes on both plate and wire should next 
be marked out and drilled. The model can now be riveted 
together, using two short lengths of yV-inch diameter wire 
for rivets. 

Note. — Filing is not allowable on the edges of tinplate and 
thin sheet-metal work, which should always be cut and finished 
direct from the shears. 

Model Q— Pin-Tray : Tinplate.— Thi^ model should be 
made from tinplate of D.C. thickness. Mark out the model 
as shown m the develop- 
ment drawing, then cut 
to the outside circle ; 
afterwards carefully cut 
away the clearance be- 
tween the sides. The 
tendency here is to over- 
cut, but this is to some 
extent avoided if a centre- 
pmich mark be made at 
the intersection of the cut 
lines. 

Having completed the 
cutting out, bend up the 
sides on a strip of mild- 
steel fixed in the vice, 
neatly fit the sides together, and finish the model by solder- 
ing the joints neatly from the inside. 

Model 10 — Quarter-Pint Cup : Tinplate. — Having deter- 
mined the diameter and height of the cup, proceed first to 
make the body. Put in the top fold before bending round; 
take care not to close the fold too tightly, and endeavour to 
obtain a neat rounded edge. Having completed the top fold, 
bend round and solder the body joint. This part is now 
rounded up on a suitable stake, it being much easier to round 
up any cylindrical body after, rather than before, soldering 




Model 9. 



256 



METAL-WORK 



the body joint. The bottom should next be carefully fitted 
into the body, and the butt joint thus obtained soldered from 
the outside. Make the handle with a fold on each edge, 
shape up on the bick iron, and solder to the body so that the 
centre line of the handle coincides with the body joint. 






Model 10. 



Model 11. 



Model 11 — Tidy-Box : Tinplate. — Mark and cut out the 
development of the model as shown in the drawmg, and pro- 
ceed to wire the top edge of the front and sides, allowing about 
twice the diameter of the wire for wiring. Wiring that is to 
be bent should have the tinplate cut where the bend occurs, 
otherwise the stretch on the outside of the tinplate causes it 
to buckle. This cut, it will be noticed, leaves the wire ex- 
posed when the bend is put in the work. Having completed 
the wiring, bend each end of this part of the model to a right 
angle to form the sides. Next bend up the bottom, fit the 



SCHEME OF WORK 



257 



parts carefully together^ and solder from the back and bottom 
of the models so that no solder shows from the outside. 

Model 12 — 8oap-Tray : Sheet Zinc. — Mark and cut out the 
parts according to the development drawing; then proceed 
to bend up the main sheets commencing from the bottom, and 




Model 12. 



completing the fold end before making the body bends. Now 
fit in the sides and solder together, noting that dilute hydro- 
chloric acid will be required for the flux. The holes should 
now be drilled in the tray-piece, after which it should be 
bent up to shape. Suitable holes drilled in the back for 
hanging complete the model. 

17 



258 



METAL-WORK 



Model 1^— Serviette Ring : Sheet Copper. — Prepare the 
copper by filing to correct length and allowing about J inch 
on the width; then mark out and file the ends suitable for 
the joint, after which the sheet should be roughly rounded 
over the bick iron and the joint fitted and brazed. The ring 



f 



7^ 
r'-t- 



j^il-%'^^% 




■^'4 



i 



Model 13. 



should then be hammered up as nearly circular as possible 
on the bick iron or other suitable stake, after which it should 
be fixed in the lathe chuck and the inside cleaned up. Now 
fix on a suitable mandril in the lathe, and clean up the out- 
side and the edges to correct width, finishing the model with 
fine emery-cloth and oil, or with the burnisher. 

Model 14 — Ash-Tray : Sheet Copper. — On account of the 
drawing and stretching of the metal when being hammered, 
the well of this model must be worked before marking out the 
edge design. 

The well is bossed out with an egg-ended mallet on the 
sand-bag or on a cast-iron block in which a suitable recess 
has been turned. As the bossing proceeds it will be found 
that the copper hardens, and will split unless continually 



SCHEME OF WORK 



259 



annealed. Having completed the well, mark out and file 
the outside design. The model is considerably improved by 
suitable bronzing and lacquering. 



—G22 



f 



J 




Model 14. 



Model 15 — Screw of Jack : Mild- 
Steel. — Cut off a short bar of mild- 
steel about \ inch greater in dia- 
meter and 1 inch longer than the 
finished model. Centre the bar as 
mentioned in the chapter on Lathe 
Work, and fix up the bar in the 
lathe; and, working from the dead 
centre, turn down about If inches 
of the length to \ inch diameter, 
following on with about f inch of 
the length to jl inch diameter ; 
then square up the shoulder so 
that the pin part of the model is 
exactly 2 inches long. Remove the 
work from the lathe, and screw the 




Model 15. Model 16. 



260 



METAL-WORK 



pin to a J -inch standard nut with the stock and dies. Saw 
off the waste metal, allowing about Jg inch, which is best 
removed by holding the screw in a lathe chuck and taking' a 
cut across the head, thus leaving the top face dead square 
with the centre line. Mark out the position of the holes in the 
head, and drill by holding the model in the vee block. Finish 
the model by fixing in the lathe and lightly filing the head 
with a smooth file and polishing with emery-cloth and oil. 

Model 16 — Body of Screw-Jack : Cast-iron. — Drill and tap 
the casting, after which it must be fixed up in the lathe on a 
screwed mandril. Commence turning by parting down both 
ends to correct length, then turn both collars to correct 
diameter, and, having made two centre-punch marks to 
denote width of the collars, cut the taper part. Finish the 

model by filing with smooth files and polishing 

with emery-cloth and oil. 

Model 17 — Knob for -Paper-Weight : Brass. — 
Cut off and centre, ready for placing in the 
lathe, a length of |-inch diameter brass bar, 
allowing about 1 inch for waste. Turn down 
the screwed portion and screw to fit the paper- 
weight with stock and dies or with screw-chaser 
in the lathe. Then, holding the screwed part 
i in the chuck, turn up the handle part, finishing 

Model 17, with the burnisher or fine emery-cloth. 



H*;^ 



IJ A 




Model 18. 



Model 18 — Skimmer : Wrought-Iron or Mild-Steel. — Take a 
length of bar metal, and commence work by forging the handle 
portion. Then determine and cut off the length of metal 



SCHEME OF WORK 



261 

The 



to complete the models and forge the hook portion 
model is finished from the forge. 

Model 19 — Poker: Mild-Steel. — Commence by forging the 
handle; then put in the twist. This is best done by heating 




Model 19. 

the desired part, gripping one end in the vice, and turning the 
bar with a lathe carrier or tap wrench. Determine and cut 
off to exact length, and complete the model by forging the 
point. 

Model 20 — Hook : Mild-Steel. — The pomt of the hook should 
first be forged down and ground on the grindstone, after which 




Model 20. 

the point bend should be forged. Then cut off to length, and 
forge the second bend. A template of the hook marked out 
on a sheet of tin is of great assistance when forging this 
model. 

Model 21 — Bracket : Mild-Steel. — This model is an exercise 
in cold bending, and before commencing work the necessary 
lengths of metal should be cut off and carefully annealed. 



262 



METAL-WORK 



iStart the model by marking out, filing to size, and drilling the 
holes in the back plate ; then prepare the top plate, and, after 
drilling the holes, bend to a right angle in the vice, after which 
these two plates should be riveted together. Now determine 
the exact length of the stay, file the ends, and turn the curves 
over the beak iron, anvil beak, or a bar of steel of suitable 




Model 21. 



diameter held in the vice; then hold the stay carefully in 
place, and with the scriber mark through the exact position 
of the rivet holes. Their centres should be punched and the 
holes drilled, after which the stay should be riveted in its 
place and the model completed. 

Model 22 — Drill : Cast-Steel. — Forge out the end of a bar 
of cast-steel to suitable size, and carefully anneal to relieve 
the forging strains; then file or grind the cutting edges with 



SCHEME OF WORK 



263 



suitable clearance angles, harden and temper the tool, and 
cut off to a suitable length. 




Model 22. 



Model 23 — Centre-Punch : Cast-Steel. — Take a bar of f -inch 
octagonal cast-steel and forge down round to a suitable length, 
allowing for the point, anneal as in the previous model, then 
cut off to length. Fix the forging in the lathe chuck, and file 




Model 23. 

up the taper and point. Now file up bright the octagonal 
sides, clean off the top, and chamfer. The model is now 
ready for hardening and tempering, after which it should be 
brightened all over with emery-cloth and oil. 

Model 2^— Flat Chisel: Cast-Steel. — Forge the end of a 
J -inch octagonal bar of cast-steel to suitable size, taking care 
i" 



1 



r 




Model 24. 



that the fiat part of the draw-down is an elongation of one of 
the octagonal sides of the bar; then anneal as in previous 



264 



METAL-WOKK 



exercises. Now cut off to length, file or grind the cutting 
edges, and harden and tem^Der. 

Note. — Cast-steel always deteriorates on the outside when 
heated, due to loss of carbon. It is therefore the practice, 
when forgmg cast-steel tools, to forge full to size, and remove 
the impoverished metal when filing or grinding the working 
edges. 

Model 25 — Try-Square: Mild-Steel. — File up the edges of the 
stock true square, and parallel, leaving the two broad faces. 
Now prepare the blade true, square, and parallel, 
and clean up and polish both broad faces. Cut 
the slot m the stock and fit the blade. Drill 
one hole through both parts and rivet lightly 
together, set the model dead square, and to 
prevent any slight movement touch the bottom 
of the blade and stock with a little soft 
solder, after which the second hole should 
be drilled, the rivet inserted and hammered 
up close. Complete the model by cleaning 
off both broad faces of the stock. 

Note. — Very little counter- 




J 

% 






%" 



Model 25. 



sinking is required for the 
rivets, but it is essential that 
they should be a driving jSt 
in the holes. 

Model 26 — Letter - Rack : 
Mild-Steel and Other Selected 
Metal. — Having completed 
the design of the outline, mark out and complete the back 
plate, drilling holes in the required positions. Then, having 
selected a suitable metal for the leaves, carefully hammer the 
face, mark out and file to size, set off the position of the 
rivet holes, check against the back-plate holes, and drill. 
Complete the model by riveting together, noting that the 
top leaf must be riveted before the lower one. 



SCHEME OF WORK 



265 



Model 27 — Callipers : 
Mild - Steel. — Calculate 
the length of metal re- 
qiurecl for each leg of 
the model, cut out two 
pieces, one for each leg, 
drill the holes, and tem- 
porarily rivet together. 
Now prepare a tinplate 
template of the outline 
of the leg, and roughly 
forge the riveted bars 
to it. When cool, file 
the edges exactly to the 
template, then remove 
the temporary rivet, 
and, tacking each leg to 
a piece of wood, clean 
off both faces. Now fit 
the permanent rivet, 
place the legs and 
washers in correct posi- 
tion, and complete the 
model by carefully 
riveting together. 

Model 2S~Kettle: 

Tinplate, with Copper 
Bottom. — Draw out the 
complete development 
of this model, noting 
that the body joint is 
directly opposite the 
spout. Then commence 
work by throwing the 
edge of the copper 
bottom on the half- 






2^ 



9" 



+ 



2^ 



+ 




Model 26. 




Model 27 



266 



METAL-WORK 



moon stake, annealing the copper as the work proceeds. When 
the edge is finished, neatly tin the inside face. Then cut out the 
development of the body, throw up the joint, roughly round 
up, fit, close and solder the jomt on both sides; then work up 
the body quite circular by striking lightly with the hide 
mallet on the funnel stake. Next make the neck, noting 



Body Joint A or B. 




Model 28. 

that the wiring is best done in the straight; then complete the 
spout, bridge, and handle. The model is now ready for 
soldermg together, the most convenient method being to 
solder first the neck to the body, next fix the spout and bridge 
into position, then solder on the bottom, finally securing the 
handle firmly to the neck by soldering down both sides. For 



SCHEME OF WORK 



267 



the cover^ take a piece of tinplate, to form the top plate^, 
larger than the finished size, and with the egg-ended mallet 
on a sand-bag knock up in it a slight boss. Find the centre 
of the boss, mark out and cut the plate to size, stiffen the 
edge by neatly soldering around it Jg.-inch diameter tinned 
wire. Now cut out and solder into position the lip ring, 
finally drilling a small hole in the centre of the boss for 
screwing the handle into position. 

Note. — This handle should be of wood or some such non- 
conducting material, and may be turned up in the lathe. 

Model 29 — Bolt with Welded Head : Wrought-Iron or Mild- 
Steel. — Take a short bar of |-inch diameter metal, heat the 
end in the forge, and jump-up about 1 inch of it to f -inch 
diameter ; then from }-inch square metal forge a ring to fit the 
jumped part of the bar, and roughly to the shape of the bolt 
head. The edges of the ring need not be welded when made, 
as they can be effectively joined when welding the ring to the 
bar. The danger in this weld is that the outside of the ring 




Model 29. 

burils before the inside comes to welding-heat, but this can be 
largely overcome if the ring is allowed to become quite cool; 
then raise the bar to white-heat, quickly set the ring in position, 
and replace both in the fire. Bring the metal up to welding- 
heat, and close the joint by a few sharp blows. Then reheat 
and hammer the head to shape. Having completed the 
forging, cut off the bar to length, and screw the end by any of 
the usual processes for producing screw-threads. 

Model 30 — Photo-Frame : Front, Brass, Copper, or Alu- 
minium ; Bach and Stay, Tinplate. — Having decided the size 
of the opening in the frame, proceed to design the outline of 



268 



METAL-WORK 



the front plate, and then work up to shape. The face may be 
polished, bronzed, frosted, or hammered, but if the latter 
the hammering must be done before marking out. Having 
completed the front plate, make the back and stay, the former 
being about J inch larger all round than the opening; solder 



I! 



-^- 



% 





Model 30. 



the stay to the back, and finally secure the back to the front 
plate. If this be of copper or brass, soldering will make an 
effective joint; but if of aluminium, the joint must be riveted, 
and the fact should be kept m mind when designing the 
outline, due allowance being made for the position and shape 
of the rivet heads. 

Model 31 — Poker : Handle and Bar, Brass or Mild-Steel ; 
End, Mild-Steel. — The design of the handle having been com- 
pleted, cut off a piece of material about J inch greater in 
diameter and J inch longer than the finished sizes. Centre 
the bar, diill a small hole in one end, and a hole y^g-inch 
diameter, about 1 inch deep, in the other end. Fix the bar 
up between the lathe centres and turn to shape, remembering 
that the end with the larger hole goes next to the bar. The 



SCHEME OF WORK 



269 



drilling of this hole before turning, and using it as a centre 
when turning, insures that the hole will be exactly true with 
the finished handle. Having completed turning and polishing 



K- 



H 




h-V-*K- 



5>' 






Model 31. 



the handle, tap the hole to receive the bar, then cut off and 
clean up the bar, screwing each end for about J inch of its 
length. Proceed now to forge the pyramid on the end piece, 



iii(rjj|_''5 



°3^^flfp/^"i ' 




Model 32. 



after which cut off to length, find the centre, and drill and tap 
a corresponding hole to that in the handle. Finally grip the 
handle firmly in the vice with lead champs, and screw the three 
parts firmly together. 



270 METAL-WORK 

Model 32 — Coal-Tongs : Mild-Steel. — Having decided the 
sizes and design of the model, forge both arms and drill out 
the rivet holes; then cut out and file up the outline of the 
spring, set off and drill the rivet holes, after which this part 
should be cold-hammered to shape on the beak of the anvil or 
the funnel stake. As this hammering alone imparts strength 
to the spring, it should be carefully done, fiat even blows all 
over the material yielding excellent results. When the spring 
feels satisfactory, complete the model by riveting it to the 
arms. 



CHAPTER XXV 

SUGGESTIONS FOE COMBINED WORK IN WOOD 
AND METAL 

1. Seed-Marker. — This consists of a small tab of tinplate 
fastened to the wood by four panel pins. 

The tinplate is usually cut from the contents of the scrap- 
box. The four holes are formed by the centre -punch. 




1.— Seed-Marker (C. M.). 

The name or number of the plant may be stamped by 
punches. 

The exercise brings in the use of snips, centre-punch, scriber, 
and steel square. 

Brass or copper from the scrap-box may be used, if avail- 
able, instead of tinplate. 

2. Bracket. — This object brings in the tools used in Exer- 
cise 1, together with folding iron (see p. 128) and hide mallet. 
The development is simple, and forms a good introduction 
to this particular branch of geometry. 

271 



272 



METAL-WORK 



The amount cut awcay, to allow the back to finish flush, 
must not be cut off, but folded under. The bracket ends may 
be shaped. The fastening is by panel pins. 




o 



/^ 



/o^ JJ 



Cut 




Cut--:3_i 



^ 



!kf 




3. — Knife-Cleaner (C. M.). 



2.— Bracket (C. M.). 

3. Knife-Cleaner. 

— The mild -steel for 
the handle is J x yV 
inch section, and, after 
being marked out, is 
drilled to a size to suit 
the screws to be used. 
The mild - steel is 
cold - bent, and care 
must be taken not to 
attempt to square a 
corner, as the steel 
is apt to fracture. It 



2k. 



SUGGESTIONS FOR WORK 



2*73 



may be bent by fixing in the vice, with clamps, or by holding 
in the folding bars and then in the vice. 

The fastening is by round-headed screws. 

The exercise forms a good introduction to the measurement 
of stock. 

4. Toast-Rack (No. 10 Gauged Tinned Wire).— The exer- 
cises include cold bending of wire and the formation of twists. 

The handle and shank are obtained by fixing the two ends 
of the wire at a point which leaves sufficient material in the 




■■\ 




4.— Toast-Rack (C. M.). 

straight to form the rack. A cylinder is then put through 
the looped end and turned until the desired twist is obtained. 

The wire is fixed as shown, and the bottom is covered by a 
slab of thin or three-ply wood. 

A similar handle and shank will be found convenient for 
other objects, such as an egg-stand. 

18 



274 



METAL-WORK 



5. Calendar (Tinplate or Brass). — This is an extension of 
development upon No 2. 




U 



L r 




i 



JJ-r 




G.— Bill-File (C. M.). 



5.— Calendar (C. M.). 

The new exercises involved are stop- 
cutting with the snips and the cutting 
of sheet metal with a cold chisel. The 
three tabs are slotted through a fret- 
saw cut in the wood, and bent back 
and fixed by panel puis. 

6. Bill-File. — The material supplied 
for this is a No. 6 knittmg-needle. 

The annealiug, pointing, bending, 
and rehardening are a simple in- 
troduction to cast-steel workings. 
Durmg the softenmg, which is done 
over a Bunsen burner, the whole of 
the colour scale will be observed. 

The base end is flattened and bent. 
This bend is let J inch into the wood, 
and the hole is refilled. 

Finish by gluing green baize upon 
the base. 

By measuring the length of the 
needle before bending, and after- 



SUGGESTIONS FOR WORK 



275 



wards remeasuring, the rule for measuring stock is con- 
firmed. 

7. Key-Rack (Brass, Copper, or Aluminium). — The shaping 
of the back is optional. The new exercises are hammering of 




-^ 



T.—Key.Raok (0. M.). 

the face upon a metal block with a ball-paned hammer and 
filing. The metal is fixed to the wood by the hooks, which 
screw through holes drilled in the metal. 

If aluminium is used, the hooks can be made very similar 
in appearance by tinning them. 

8. Grater (Tinplate). — The centres of the 
punch holes must first be marked in the 
flat, and punched with an |-inch hollow 
punch upon either a block of wood or 
lead. The curved surface is obtained 
by bending it over a wooden cylinder. 
The metal is fixed to the wood by panel 
pins. 

Sufficient tinplate can be obtained for 
this exercise by cutting up an old cocoa 
tin. 




-^ 



*T-^ 



1- 



9. Letter-Rack (Zinc). — The metal used 
for this is soft and easily worked, but 
the fact that it possesses a distinct grain 
requires notice, and also that the annealing 
is different from other metals. The bend 
is formed in the folding bars, and the screw holes are formed 
by an -|-inch hollow punch. 



8.— Grater (C. M.). 



276 METAL-WORK 

The front of the brackets may be decorated by bossing or 
piercing. 




9.— Letter-Rack (C. M.). 

10. Toilet-Fitting (Brass Wire, 20-Gauge Plate).— This is a 
repetition of wire-bending. The wire and plate in this case 




o 



H: 




10.— Toilet-Fitting (C. M.|j. 

must be annealed. This can be done over the Bunsen 
burner. 



SUGGESTIONS FOR WORK 



277 



The groove in the brass plate to receive the wire is obtained 
in various ways^ but perhaps the simplest is to form a groove 
in the face of a piece of hard wood, lay the metal upon it, and 
hammer with either a creasing hammer or the straight pane of 
a small ordinary hammer. 

The plate may be shaped if desired. 




Wood-end Grain in 
Direction of Arrow 



O 



11. — Hatpin- Stand (C. M.). 



11. Hatpin-Stand (Brass). 
— This involves the bending 
of sheet metal to sharp 
corners, for which purpose 
it requires annealing. 

It also brings in the measure- 
ment of the circle. 

12. Reel-Stand (Mild-Steel). 

— The material used in this 
exercise is slightly thicker 
than previously used. The 
bend can, therefore, only be 
got by heating. The use of 
the hack - saw is also in- 
volved. Quarter-inch bolts 
and nuts might be utilized 




12.— Reel-Stand (C. M.). 



278 



METAL-WORK 




o 


o 


o 




o 


o 


o 


o 


o 




o 


o 


o 


o 


o 




13.~Soap.Tray (C. M. 




© 



14. — Cajtple Bbacket (C. M.)- 



SUGGESTIONS FOR WORK 



279 



if desired. The nut should be screwed on and soldered, and 
the head sawn off. 

The dimensions are determined by the size and number of 
reels. 

13. Soap-Tray (Zinc). — The holes are obtained by the aid 
of a rose bit or by the aid of the folding bar and punch. 

The size is determined by the 
stock size of the bars to be used. 

14. Candle Bracket (Tinplate 

and Brass) . — The back panel is 
of tinplate of good quality, and 
is polished to act as a reflector. 

The brass is hammered to add 
a springiness. 

The design of both back and 
shelf panel and candle -holder 
is left to the student. 

15. Match Bracket. — This in- 
volves the use of drill and 
countersink, and includes a bend 
of greater width than has been 
previously used. 

An alternative shelf of alu- 
minium for tooth-brushes is 
shown, which involves the use 
of the hack-saw. The spacing 
of the slots is determined by 
the circumference of the brush 
in revolving. 

Any shelf for a particular purpose may be used instead of 
those shown, the size depending upon the article or articles 
to be held. 




TTT 



o 



Alternative 
Shelf 



15. — Match Bracket (C. M.). 



16. Towel Roller (Mild-Steel). — Curved filing is again in- 
volved. The centres are marked for pin slots and fastening 



280 



METAL-WORK 





16.— Towel Roller (C. M.). 



I 






-4-^' Eivets -A- ] 



^60 



nun. 



-SO 



mm. 



17.— Paper-Knife (C. M.). 



''''^^' '"tr:.r7:aL- .Bffi^^^BH . •. .' -■.'.:■<»■ Lunl 





18.— Photo.Framb (C. M.). 



SUGGESTIONS FOR WORK 



281 



screws^ and the curves are scribed. The holes are now drilled, 
and a slot is cut to one of the pin holes. 

The pins are formed by screwing two ordinary screws, the 
required distance, into the ends of the cylinder, and afterwards 
filing off the heads. 

The size between the brackets must be determined by the 
width of the towel. 

17. Knife (Brass). — The operations of drilling and counter- 
sinking are repeated, and riveting is introduced. 

One of the plates is marked out slightly larger than the 
handle, and the centres 
are marked for the rivets. 

The two pieces are now 
placed together, drilled, 
and countersunk. The 
marked one is now placed 
in position, and the holes 
in the wood are drilled 
through the holes in the 
brass. The riveting and 
filing are now done. 

18. Photo-Frame (Tin- 
plate) . — A rather more 
complicated development 
is necessary than that 
previously used. The use 
of flux and solder is also 
introduced. The whole 
of the bends are formed 
by the aid of the creasing 
iron and mallet. 

The leg may be 
strengthened either by 
folding or wiring. 

The semicircular foot 
of the stand is turned. 





19.— Ash-Tray and Match-Stand (C. M.). 



282 



METAL-WORK 



«i-'- -r 




20.— Inkstand (C. M. 




21.— Clinometee (C. M.). 



SUGGESTIONS FOR WORK 



283 



after wiring or folding, over a cylinder of convenient size. 
The wire, if used, should be tinned. 

The back is fastened to the woodwork by means of screws. 

19. Ash-Tray and Match-Stand (Zinc). — The geometrical de- 
velopment is the chief feature of this model. It also brings 
the question of the grain of zinc more forcibly into account, 
and requires a different flux to that previously used. 

The size of the conical holder is determined by the size of a 
match. 

20. Inkstand (Brass or Aluminium). — If brass is used, it 
must first be annealed. The development is then drawn 
upon the material, and the holes are drilled. Those for the 
pens and pencils are determined by the size of the pen-holder 
or pencil. The flange is then mitred, and the bevelled portion 
either sawn or cut by the fiat chisel. 

The bending is now done as in previous exercises, and the 
metal cleaned by dilute nitric acid. 




22. — Printing Frame (C. M.). 

21. Clinometer (Mild-Steel, Brass).— The metal-work in this 
model includes J-inch bolt and fly-nut, brass washer made of 
brass from the scrap-box, a brass arm, and four mild-steel 
stays. 



284 



METAL-WORK 



The arm involves the piercing of a hole through the surface 
of sheet metal by the aid of the flat chisel. 

The stays may be twisted to relieve the straight lines if 
desired. 



D n D 



II ■ I f I II I I 



^lEL 



I I 1 : 




23.— Capstan (C. M.). 



22. Printing Frame (Brass). — This model involves the 
making of simple hinges, and also the hammering of brass to 
form^^springs. 



SUGGESTIONS FOR WORK 



285 



The making of a hinge is described in the metal-work course 
on p. 252. 

23. Capstan. — This model is used in the mechanics lessons. 
The ratchet-wheel and washers are of mild-steel, and the spring 
is of cast-steel. 




24.— Balance (C. M.). 

24. Balance (Mild-Steel and Tinplate). — The arm involves 
a new form of cold bending. This is done by placing the strij) 
over two blocks of wood about 1 inch apart, and striking the 
edge of the metal over the space. 

The pan is bossed out upon a sand-bag or prepared block 
of wood, and then cut to sha23e. 

The cam is of mild-steel, and as shown. 



CHAPTER XXVI 

NOTES ON TEACHING METHODS 

In dealing with the subject of metal- work as practised in the 
schools of to-day, it may be well to begin with a glance at 
handicrafts in general, and the reason for their inclusion in 
the curriculum of almost every public school in the kingdom, 
whether primary, secondary, or " central ^^ schools in England, 
or " supplementary " schools in Scotland. 

The subject undoubtedly suffers from the varied, ever- 
changing, and misleading names attached to it. Glance for a 
moment at the list : 

1. Manual instruction. 

2. Manual training. 

3. Slojd. 

4. Handicraft. 

5. Educational handwork. 

6. The various branch names given to separate 

sections, such as cardboard modelling, wood- 
work, metal- work, etc. 

And yet the whole is, or should be, one united and complete 
scheme which only one term justly describes. That term is 
" education.'' 

Let us look at the terms and briefly analyze them : 
1. Manual Instruction. — This strikes at the very founda- 
tion of the system; for it is contended, and rightly so, that 
under this scheme of education the student, no matter how 
tender in years, is in the highest degree self-taught — by obser- 
vation, by direct contact with concrete things rather than 

286 



TEACHING METHODS 287 

abstractions, and by a system of complete progression which 
is the very art of education. 

2. Manual Training. — Whilst less objection can be taken 
to this term than to the first, it is still far from being a true 
definition. If the training were only manual to a certain 
extent, we should be developing the animal rather than the 
intellectual being. But since any properly-acquired know- 
ledge is bound to develop the intellect equally with the physical 
nature, and as dealing with the practical things of life by young 
children has a value considerably under-estimated by the 
boldest reformer, we must conclude that this term is also 
deficient in its description of our aims. 

3. Slojd. — To understand thoroughly how far this term 
misses the mark, an explanation of the word itself is necessary. 
The word is Swedish. No word in the English language can 
describe it. In the North of Scandinavia the chief occupation 
of the people is agriculture. Wages are so small that the 
natives find difficulty in keeping body and soul together even 
when the income is regular. During the long winter night of 
three months agricultural pursuits are out of the question, and 
yet the people must live. So the days of darkness are occu- 
pied at the fireside in whittling with a knife, from small pieces 
of wood, bone, or other material, articles which, after crude 
decoration, generally in very bright colours, are sent into the 
towns for sale. The late Herr Salamon, in studying social 
conditions, came to the conclusion that one at least of the 
functions of education was to equip a child for after-life, and 
in his wisdom he determined that children should be trained 
so as to possess a better earning power. Now, these people 
were agricultural labourers, but they also earned a certain 
proportion of their income from this class of wood-work. 
They were therefore Sloj dares, or amateurs. It will be seen, 
therefore, that our system is much wider in its ideal than the 
word Slojd indicates. 

4. Handicraft. — Here, again, the purely manual side is to 
the fore instead of being secondary. The exercises in handi- 



288 METAL-WORK 



"% 



craft are only useful when attached to the higher or intel- 
lectual side of man, so that this latest Government term must 
be written down as " found wanting/' 

5. Educational Handwork is the name adopted by the 
strongest advocates of the system themselves, but it defines a 
distmction which is out of place, as no other mental culture 
will give that acute perception, clear judgment, and instant 
definite decision, which are so necessary to the well-balanced 
mind. Under these circumstances it is right and proper that 
the single and definite term " education "'' best fits the situation. 

The world has boasted, and still boasts, of its fine workmen 
and thinkers who lived generations before the days of organized 
national education. The only training these men had was 
derived from the part they took m the practical things of life. 
But times have changed. Years ago a boy had to take his 
part, at the earliest possible age, in helping to provide the 
necessaries of life for the family. In doing so he met many 
phases of work, such as hunting for the provision of food and 
clothing, and building for shelter ; in fact, he came into direct 
contact with every kiiown branch of labour, and by domg so 
fitted himself for that sphere of life in which he was destined 
to find his highest happiness and well-being. This is the 
education which we have neglected for many years ; it is the 
education we are endeavouring to secure again in a better 
form. 

The stage so briefly outlined might be described, in the 
biographical review of education, as the family life. As 
families increased in number and congregated in groups, the 
second stage made its appearance, one family providing all 
the food, another all the clothing, another all the dwellings; 
so that, whilst a boy was still in touch with all branches, he 
was only in direct contact with one branch. Then towns 
developed from communities, and the chances of keeping in 
touch with all branches of life diminished. Whilst this life was 
not so good as the communal or famity life, it was better 
than the national life which followed, by which a district took 



TEACHING METHODS 289 

over the complete production of particular commodities. 
To-day we have in this country many examples of this form. 
Birmingham supplies small goods and hardware, Nottingham 
lace, Northampton boots. True it is that natural conditions 
play a large part in this state of things, but it is still true that 
education, in its highest sense, has also suffered by the arrange- 
ment. 

In dealing with this aspect of the subject, there are some 
things which the instructor must always bear in mind. 

First, he must remember that the whole of his students 
have previously received, or are receiving concurrently with 
metal- work, a course in wood-work, cardboard, clay, etc. 
He can therefore presuppose some technical skill and know- 
ledge, but he should at the same time remember that he is not 
dealing with a class of experts, but with " students,"" and 
that at times more is learnt through a mistake than by 
apparently successful work. 

There is an old North Country saying which instructors 
would do well to remember: " The man who never made a 
mistake never made any thing. "" Mistakes may be turned to 
most valuable account if handled carefully and in the proper 
spirit. The prevention of mistakes is by no means advocated 
upon all occasions, and it behoves the teacher to think care- 
fully before interfering with a pupil who is working upon some 
unorthodox or " unrecognized " lines. If convinced in his 
own mind that no personal risk is involved, the teacher 
would be well advised, in most cases, to allow the boy to 
proceed, and afterwards to compare carefully his processes 
and result with those of a more skilful worker. 

A boy, if not allowed to work in his own way, will, in defer- 
ence to the teacher's authority, carry out his instructions, 
but the question of whether the boy's own way would not 
have been equally successful is left unsettled. Would it not 
be better, therefore, to allow the method of " trial and error " 
to proceed under supervision, and afterwards to discuss the 
matter and show the benefits of the conventional method, 

19 



290 METAL-WORK 

rather than tempt the pupil to experiment privately under 
probably less favourable conditions ? 

Suggestions as to method by the teacher at too early a stage 
might probably have the effect (1) of giving the lazy boy too 
much help rather than throwing him upon his own initiative ; 
(2) of confusing the minds of the majority of the boys by too 
much detail. Independence of thought and action is one 
of the main features to be encouraged in handwork, and to a 
boy entering the world of crafts the acquisition of such in- 
dependence will be a valuable asset. 

As more complicated tools, machines, etc., are introduced, 
this point requires still more careful consideration, as other 
dangers appear, and it is here that the qualities of the skilful 
teacher will be evident. It is perhaps sufficient, from a dis- 
ciplinarian point of view, to say: " You must not do that, you 
must do this."" But from the educator the boy is entitled to 
a reason or an explanation. By every means the teacher 
should encourage the growth of self-reliance in the lower 
forms of handwork, and should give increasing encouragement 
to the same spirit as the work develops. 

Handwork teachers are in the enviable position of having 
small classes to handle — numbers which allow individual in- 
struction. Group or class teaching at certain stages is an 
advantage, but the occasions must be selected. In intro- 
ducing some new tool, machine, material, or o]3eration, it is 
well to gather all students together and explain the chief 
points to be observed, and to state such facts as cannot 
reasonably be acquired by experience, leaving any point 
which ought to be discovered by investigation for future 
individual talks with the pupils during the working. The 
differences in the mental abilities of the pupils can be best 
dealt with in this way. It is better to leave the boy " too 
much "" to think about than " too little. "" 

Many teachers make the mistake in class teaching of work- 
ing to the standard of their worst pupils, forgetting the im- 
patience of, and waste of time by, the others. 



TEACHING METHODS 291 

In many cases, in individual teaching, the teacher fails 
through inability to come down to the level of his pupil. 
The successful teacher is he who can adapt himself, for the 
time being, to the student in hand. 

The boys themselves are not sufficiently made use of in 
teaching. They talk to each other in a language more easily 
understood, and, having the advantage of recent experience 
in overcoming a particular difficulty, they often succeed 
in helping duller companions where the teacher has failed. 
This difference in ability of students is one of the problems 
of education. In the ordinary school subjects, where large 
classes are general, it means that the smart boy has much 
" marking time " to do, and the duller boy has to pass many 
things either half understood or missed altogether. As ilhis- 
trating this statement, reference need only be made to the 
frequent publication in the Press of " school-boy howlers.'" 

This difficulty is not present in the handicraft-room. There 
is not the necessity for keeping the students " level.'" In 
the past days of handwork each boy performed the same 
manipulation or exercise at the same time, and, as the 
pace was set by the slowest boy, much time was lost. Now, 
after certain fundamental exercises have been performed 
to give some skill in tool manipulation, each boy is allowed 
to strike out along his own lines. 

His previous knowledge of mechanical drawing, obtained 
in his woodwork lessons, is valuable in the metal-work room, 
and considerably assists the individual method of education. 
He now designs his own pieces of work; and in this he may 
be guided by a list of exercises or tool manipulations drawn 
up in carefully graded order of difficulty. This list should 
contain no names of models, but, in line with the exercise, 
may include an illustrative sketch which will show what 
the exercise is, and nothing more. It is unfair to the pupil 
to give a complete model if it is intended that he should 
design his own, as any example shown may cramp his out- 
look and add considerably to his task. Having fixed upon 



292 METAL-WOKK 

his subject, the pupil will first be expected to sketch- his 
idea upon paper or blackboard. This helps to train him 
to build up in his mind clear ideas and to express them 
readily; at the same time it assists him towards a settlement 
of sizes and proportions before commencing his working 
drawing. 

In many instances the pupil will present a sketch for 
approval which is entirely beyond his skill. Here, again, 
great care and tact are to be exercised. By carefully chosen 
hints and criticisms, the teacher should be able to bring the 
work within the powers of the pupil without affecting the 
germ of the idea, and without discouraging him. 

By varying the degree of elaboration of the models, it is 
possible to avoid too great a gap arising between the smart 
and the dull boys. This gap presents no difficulties so far as 
practical working is concerned, but if too wide it makes 
group lessons of little value, because a slower pupil would 
then be taking lessons on tools, machines, or materials, long 
before he would be ready to use them. 

The boy^s progress is more important than group lessons. 
In metal-work the materials vary to a greater extent than 
in any other branch of handwork, and the manipulations are 
also more varied. This may be looked upon as a help rather 
than a hindrance. The class may be divided into, say, three 
groups, taking the advanced pupils and leading them as a 
small group, and doing the same with the intermediate and 
lower pupils. 

In these group lessons it need not be assumed that a pupil 
must be thoroughly acquainted with each piece of material 
or tool or machine before using it. For instance, it matters 
little to a boy making a tray or photograph frame how copper 
is produced, where it is found, its market form and price ; but, 
on the other hand, it is of importance that he should observe 
its nature whilst working it, and that he be told that it can 
be made soft again, and how. 

Whilst set courses for pupils are not advocated, there is 



TEACHING METHODS 293 

an undoubted value in binding a pupil at times to certain 
fixed conditions, to accustom him to the presence of limita- 
tions. But in all such cases the barest outline should be 
given, leaving the selection of a suitable design to the pupil 
himself. In all cases where a boy is asked to work within 
limits supplied by the teacher, he should, however, know the 
use of the finished article, so that he may appreciate the nature 
of the construction, the proportions, and the relative position 
of the parts. 

The work should, as far as possible, attach itself to the 
usual school studies, and it is essential that the handwork 
teacher should be acquainted with the ordinary school if his 
teaching is to bring full value. So, also, the class teacher 
or form master should be acquainted with the work of 
the manual training room. Most branches of the school 
curriculum can be assisted by the practical work of the 
pupils. 

Geographical knowledge is helped by impressing on the 
mind of the pupil the districts from which ores are obtained, 
by showing reasons for the development of industries in 
particular districts, and by demonstrating how the advance 
of metallurgy may change some industrial districts. For 
example, the present-day fuel used in iron production has 
transferred the industry from the forest districts to the 
coalfields. 

In history the advance of science and the enlarged know- 
ledge of metals have been important factors. Whilst this 
advancement may have been the result of general progress, 
it has also, in its turn, been the cause of further progress. 
The history of any natural science greatly resembles the 
history of a nation. In each instance the first object is to 
obtain knowledge of causes, and afterwards to frame laws. 
There is great scope for the imagination when dealing with 
the fascinating history of metals and their discovery, and the 
pupiFs interest is at once stimulated. He must put himself 
into the atmosphere of the times m which the discoveries 



294 METAL-WORK 

were probable, and it is the work of the teacher to create 
that atmosphere. Like the weird accounts of prehistoric 
times, the history of the discovery of metals must have been 
the product of vivid imagination. 

Handwork and mathematics are inseparable. The verifica- 
tion of most of the mathematical formulae is bound to come 
in his work, and the advantage lies in the fact that the said 
formulae are now based upon reasoned knowledge which is 
the outcome of experiment. 

Tinplate work provides the simplest medium for models 
to prove volume, forge and wire work for calculating measure- 
ments based upon the circle, lathe work demonstrates pro- 
portion, and by a system of algebraic terms instead of measure- 
ments these terms can be converted into concrete things 
instead of difficult abstract signs. Triangles, arcs, segments, 
wedges, and other forms, are constantly recurring, and their 
areas, volume, etc., are obtained hj practical methods. It 
can thus be demonstrated that the abstract was derived from 
the concrete. 

In the workroom examples of many of the principles of 
science can be found, and in most cases in a convenient state 
for finding their value. The lever is found in the vice, forge 
handle, spanners, snips, shearing machine, lathe, grindstone 
handle. Lever power can in most of these examples be easily 
demonstrated. d | 

The inclined plane appears in the vice, the screw, the drill, 
etc.; whilst a splendid example of the combined forces of 
lever and mclined plane is afforded in the vice, and also in 
screwing up nuts with spanners. The mechanical advantage 
of gearing is immediately evident in the lathe, drill, and 
grinder. 

Centrifugal force can be shown on any fast-spinning wheel 
by the application of liquid near its centre. 

Examples to illustrate momentum, linear velocity, principle 
of the wedge, transmission of joower by belting, specific 
gravity, etc., are also to be found. 



TEACHING METHODS 295 

In working, examples will be continually appearing both 
in operations and in completed models, and may be obtained 
from the pupil by questioning. 

These working examples are better than any apparatus 
erected merely for experimental purposes. 

Handwork and art are inseparable also. When handwork 
is really joined with art, a great advance in the teaching of 
this subject may be expected, because designing will be looked 
at from the practical point of view as well as from the artistic. 
In designing for practical work, two considerations must 
come before what is usually termed the " artistic side."" 
These are (1) the essentials of the model, so that it may best 
fulfil its purpose, and (2) the possibilities and limitations of 
the material. 

In the metal-work room many splendid subjects for object 
drawing may be found, and, as the pupil has handled and used 
the objects, he should be better able to draw them. 

The workroom puts the breath of life into mechanical 
drawing. This branch, coming more directly under the 
supervision of the instructor, requires his serious considera- 
tion. It must always be remembered that the pupil has 
some experience in this branch of the work. 

Questions are contmually arising, such as — 

1. Must the drawing always precede the practical work ? 

2. Having once completed the drawing, should any devia- 
tion be allowed ? 

3. Should drawings be made for tinplate work ? 

4. What form should the drawings take ? 

We shall discuss these points one by one as briefly as 
possible. 

1 . Must the drawing always precede the 'practical work ? 
This is a question in which the capabilities of the boy must 
be considered, but as a general rule the answer is " Yes."" 

All boys are not equally capable, nor can all boys build up 
the finished work in their minds, and unless they can do so 
the work cannot be considered satisfactory. 



296 METAL-WORK 



It is better at the commencement of the course to allow 
the pupil to proceed as far as he possibly can with the cbawing, 
and then to commence his work and run the two together. 
By this system it may reasonably be expected that his in- 
creasing knowledge and observation will ultimately lead him 
to complete his ideas through his pencil and paper before 
he commences his practical work. 

Another reason why the answer should be " Yes " is that 
the practical work is the test of the drawing, and should 
therefore come second. 

2. Having once completed the drawing, should any deviation 
be allowed ? The aim of the work is to make any deviation 
unnecessary, but in the earlier stages the pupil can see pro- 
portions and shapes better in the actual model, and by 
suggesting alterations he is giving evidence of thought and 
observation. Where the alterations are suggested by the 
pupil, therefore, and are found to be improvements, they 
may be allowed, and the drawing should be modified to express 
the proposed alterations. 

It might be mterestmg at times to preserve both the 
original and modified drawings for purposes of comparison. 

3. Should drawings be made for tinplate work ? Unless 
the object is of some simple geometrical design, the answer is 
agam " Yes.'' 

In simple trays, cubes, prisms, pyramids, cones, etc., it 
will be found convenient at times to make paper develop- 
ments first; but in other cases it is not essential to make 
working drawings for record, as the accuracy and finish of the 
drawing will be proved by the quality of the finished object. 

Again, seeing that the finished object is the proof of the 
drawing, why put it upon paper when the tinplate is so con- 
venient ? It has the added advantage of giving confidence 
and definiteness of action. Where the objects are of odd 
and complicated shape or only partly of tmplate, it is better 
to make finished accurate drawings of the developmental 
t3^pe. 



^ 



TEACHING METHODS 297 

4. What form sJiould the drawings take ? All forms of 
mechanical drawings should, if possible, be used. In some 
instances the nature of the work will determine the style. 
Tinplate work is often best shown by development. In forge 
work, tapered scrolls are best drawn to finished shape, and 
also in development. 

Accurate orthographic projections arc best suited to some 
work — e.g., matchbox-holder, and oblique and isometric 
projections for rectangular objects. 

Scale drawing is important, and full-size, enlarged, and 
reduced scales should be used. 

In the metal-work stage of drawing strict accuracy should 
be expected, and a high standard of draughtsmanship ought 
to be the ultimate aim. 

We now come to the question of " notes."' Whilst the 
blackboard is valuable during a lesson to demonstrate by 
means of a sketch, or to make occasional notes for revision 
at the end of the lesson, it is not good to allow the pupils to 
" copy "' notes. It is better to allow them to make their 
own notes, for by this means the instructor is able to determine 
whether the essential points under review have been grasped. 
The best plan to adopt is to make the notebook almost the 
private property of the pupil, and at times to aid him in the 
selection of matter for entry. 

The question whether metal-work should be a subject or 
a method is not so keenly discussed as in other branches of 
handwork. Cardboard work, for instance, is carried on in 
some schools, but does not appear upon the time-table, 
because no special lesson is devoted to it. As occasion re- 
quires, the materials, which are stored m the classroom, are 
brought out and some problem demonstrated. With the 
harder, heavier materials and larger tools used in metal-work, 
such a plan is out of the question. 

The metal-work is heavy in its nature, and, except in tin- 
plate work, does not lend itself to quick folding and shaping 
like cardboard and paper lend themselves. When models 



298 METAL-WORK 

for teaching purposes or for demonstration are necessary, they 
are usually larger and take more time to prepare. We may 
conclude, therefore, that this subject must be taught as one 
of a correlated group of subjects, to be used as a method on 
all possible occasions. 

The workroom should, however, be available at all times 
for experimental and demonstration work, and the instructor 
read}^ to render all possible assistance, either personally or 
through his boys, in efforts which will be of value in any other 
department of the school activities. 

The degree of accuracy to be aimed at in the metal-work 
room is another matter round which many discussions have 
been waged. 

It is a generally accepted fact that the greater the resistance 
offered by a material, the greater the accuracy which can be 
attained. If this be so, and the preliminary training in hand- 
work has been of any value, a high standard should be expected 
in metal-work. The policy of " near enough '^ cannot be 
allowed to enter. But mistakes will take place, and if the 
instructor on investigation is satisfied that neither carelessness 
nor inattention has contributed to the divergence from original 
sizes, he may still allow the work to proceed so long as the main 
features of the original are preserved. Through all, the fact that 
he is dealing with pupils and not experts must be kept in view. 

Under the system of allowing pupils to design their own 
models, very little effort is needed to maintain interest, except 
in the case of larger models for demonstration. In this case 
it is better to select two or more pupils, according to the 
amount of work involved, to assist, and to allow them to 
nominate which shall act as working " foreman."" 

When an individual pupil wishes to undertake a large 
model by himself, the instructor may arrange that it be 
finished in parts, and may then assemble the parts at the end. 
As each fresh part is tackled, and as the wholp comes nearer 
completion, the keenness will generally be found greater 
than at the commencement. 



TEACHING METHODS 299 

In many models, when it is found that some other material, 
such as wood, would be useful for certain parts, it would be 
better to use wood rather than to make the complete object 
either absurd or unsatisfactory by insisting upon metal, and 
metal only. No one material can be the best for all purposes. 

In reply to the constant inquiry made by many people who 
were educated under older ideas and methods, and who are 
always asking, " What does all this manual training mean ?'' 
the teacher should be ready to prove that its chief aim is to 
turn out men — men who can grapple intelligently with the 
many problems of life in an industrial world. The object is 
not to turn out half -trained apprentices to any particular 
trade. 

If we can teach a boy to reason intelligently, we have done 
much. 

The old system of book-learning has failed in so far as it 
has proved an insufficient weapon in these more exacting 
days. 

Sir Philip Magnus some years ago, in a report to an educa- 
tion conference, wrote: 

" A literary training is not the best preparation for the 
pursuits in which a large proportion of the population are 
now engaged. This (literary) training is the survival of a 
method well enough adapted at one time to those who alone 
received education — i.e., the English gentry and the nobility — 
but unintentionally extended to the other classes, who, on 
account of the difference of their pursuits, require a totally 
different system of education.^' 

The same writer at another time stated : 

" People often talk and write as if school time should be 
utilized for teaching those things which a child is not likely 
to care to learn in after-life, whereas the real aim of school 
education should be to prepare, as far as possible, for the whole 
work of life. It is because the opposite theory has so long 
prevailed that our school training has proved so inadequate a 
preparation for the real work of life.'' 



300 METAL-WORK 



^ 



Although written many years ago^ nothing could be nearer 
the trvith to-day. Education should train the boy to think 
and act with precision and exactness^ and should tiain him to 
express his thoughts in an intelligent and clear manner, 
whether the expression be by written words or through some 
form of craft. If this be done, the boy will be better fitted, 
later on, to take his place in the affairs of the world; and 
much better able to grasp life's problems. 

By this training he will be more capable of erecting 
durable superstructures of thought and knowledge, because 
their foundations will have been built by his hand. 



CHAPTER XXVII 

NOTES OF LESSONS AND USE OF BLACKBOAED 

In dealing with group or class lessons on specific materials, 
tools, or processes, the teacher has a few points to keep in 
mind. 

Group teaching is a great saving of time if the matter is of 
general interest, but the individual must never be lost in the 
group. 

Pupils are not as empty barrels waiting to be filled; there- 
fore the lessons must never be allowed to deteriorate into 
lectures. 

The manner in teaching is as important as the matter. 
The teacher himself must be interesting if he wishes his 
subject to interest the pupils; he should be keen, alert, 
eager, and forceful; then he will find his spirit will infect 
his pupils. 

He must frame his questions carefully, and present them 
in studied sequence. A pupil cannot be expected to give a 
clear answer to a badly-worded question, and the whole system 
of statements and questions should be such as can be used by 
the boy as a basis for individual investigation on future 
occasions. The teacher should always endeavour to build 
upon any knowledge the class may have. The state of a 
pupiFs mind is often shown by his answers, and by his 
questions, and the alert teacher will be quick to grasp all 
these seemingly small matters. 

The question of order during these lessons is one which 
never worries an interesting teacher, and any unsatisfactory 

301 



302 METAL-WORK 

discipline is probably due to the teacher's lack of power to 
make the subject interesting. 

He must know his subject, take pains to prepare it, and 
carefully handle the prepared matter. In the handicraft- 
room he has a most fascinating subject for boys. It is new. 
It is something they are keen upon, and something about 
which they have vague ideas. Full value should be given 
to any information volunteered, or the pupil may refrain 
from offering any, and the teacher thereby lose a valuable 
asset. 

The time usually devoted to a lesson in a workshop is 
about thirty minutes, and this is the amount of time usually 
stated in examination questions. The City and Guilds of 
London Institute Examination Reports often state that the 
amount of matter put down to be taught in that time is 
excessive. 

In a first lesson on any subject the amount of matter which 
can be covered in half an hour is small, but it should be 
fairly general. Suppose, for instance, the subject is pig- 
iron, it would be unwise to make a full series of notes 
upon the material and to cover the first few " headings."' 
It would be better to take the whole data and go generally 
through them, dealing chiefly with the observations of 
the scholars and drawing attention to any outstanding 
features. 

In subsequent lessons the general data can be revised, but 
this time the lesson will deal more with details, and with the 
closer and fuller observations which the scholars have been 
able to make in the light of the previous lesson. 

As an example, the following notes show the amount and 
nature of the matter for a first lesson on pig-iron. 

The notes refer to the process in its full form. In many 
districts Items 1 and 2 of the " Treatment of Ore " are 
omitted. 



NOTES Ot LESSONS 
SUBJECT— PIG-IRON. 



303 



Heads. 



Materials. . 



Treatment of ore 



Process 



Matter. 



Pig-iron is made in a blast- 
furnace. 

1. Ore. — Got from the 
earth. Iron not in pure 
state. Ore needs 
" smelting " 

2. Coke.' — -Used as fuel. 
Wood was originally 
used. 



3. Limestone. — Used as 
flux. To separate im- 
purities from iron. To 
reduce ore to a form 
in which it will " flow " 
out. 

1. Washing. — To remove 
the lighter, looser im- 
purities, such as clay, 
sand, etc., and leave 
the heavier ore. 

2. Breaking. — By ma- 
chine. Small pieces 
more easily smelted 
than large pieces. 

3. Roasting {Calcination). 
— To remove water, 
organic and other vol- 
atile matter. 

1. Charging. — Consists of 
placing mixture of ore, 
coke, and flux, in bell, 
and dropping into fur- 
nace. 

2. Smelting. — Warm air 
(blast) enters at bottom 
and rises through the 
mixed material. 



Method. 



Educe these points and 
compare with other 
products, such as tim- 
ber, gold, coal. 

Obtain from scholars the 
consequences of wood 
as fuel upon the in- 
dustry of present-day 
proportions. Educe 
also that change of 
fuel would move the 
industry from forests 
to coalfields. 

Show slag, and educe that 
it contains most of the 
impurities. 



Educe the reason for pro- 
cess, and compai'e with 
gold-digger's washing 
pan. 

Educe this, and compare 
with road metal for 
size. 

Educe this and also the 
probable result of 
smelting damp ore. 



Sketch furnace with bell, 
and educe the fact of 
the mixture being 
spread as it falls. 

Add tuyeres to sketch. 
Educe the effect upon 
mixture, and show that 
coke being burnt keeps 
the mass open. 



304 



METAL-WORK 



SVBJECT—TlG-mO^— Continued. 



Heads, 


Matter. 


Method. 


Process (con- 


Hottest at bottom. 


Educe this. 


tinued) 


As fuel burns, the ore, 


Educe this from the 




etc., melts and moves 


sketch. 




downwards. 






The lighter molten 


Compare pieces of pig- 




slag floats over the 


iron and slag for weight. 




heavier molten metal. 






3. Tapping. — Slag is re- 


Add notch to the sketch. 




moved first through 






slag-notch. 






Iron withdrawn 


Add tapping - hole to 




through lower notch 


sketch. 




(tapping-hole). 






Iron runs into pre- 


Sketch these, or mould 




pared beds. 


in sand. 




Called " pigs" from 


Educe this. 




shape of back. 




Products . . 


1. Pig-iron. — 'Is of crys- 


Educe this and compare 




talline structure and 


with wrought-iron. 




very brittle. 






2. Slag. — Contains most 


Educe this. 




of the impurities. 






3. Gas. — Used for heat- 


Obtain how. 




ing blast. 






Hot blast performs 


Educe this. 




work quicker than cold. 




Uses of the crude 


Of no use in present 




pig-iron 


state. 






Still contains too 


State this. 




many impurities, chief- 






ly carbon. 






Used as a base from 


Educe likely processes. 




which purer forms are 






made. 






Further purifying 


Show specimen. 




produces wrought-iron. 






Wrought -iron con- 


State this and educe effect 




tains no carbon. 


of carbon. 




Removing all other 


Show specimen and com- 




impurities, and leaving 


pare with wrought- 




a fixed percentage of 


iron. 




carbon, produces steel. 





NOTES OF LESSONS 305 

These notes are arranged in the old " Notes of Lessons " 
style. It is the method expected by most examining bodies. 
It will be noted that the heads are first fixed upon, set down 
in turn, and underlined or written in red for convenience. 
Following each heading is the " fact "" or " matter " con- 
nected with it. This column must be carefully composed 
and fairly fully written. In a parallel column, marked 
" Method/' the method of arriving at or illustrating the fact 
is stated. 

Still keeping to pig-iron, a later lesson could be covered by 
the same headings, and, as has already been mentioned, more 
detail could be filled into the matter, based upon the inter- 
vening observations or investigations of the pupil. 

The history of the iron trade in this country would form 
another interesting lesson for older pupils, making use of the 
fact that formerly the chief iron-producing districts were 
near the forests, whilst to-day they are near the coalfields 
and waterways. 

Blast and the history of its production would also bring in 
the historical side, from the plain blowpipe, the skin bags of 
the Egyptians, bellows of the Romans, wooden box piston of 
the Chinese, the Catalan forge of the Pyrenees, to the 
present-day blowing engine and hot blast. 

In the notes of lessons upon processes, the whole series may 
be dealt with, unless a convenient break presents itself. As 
another example, the following notes upon the makmg of a 
flat chisel will serve to illustrate what is meant. In this 
instance the hardening and tempering might be left for a 
a future lesson. 

These lessons differ from those on materials in that the 
notes must be followed through or divided at some convenient 
point as stated. 

It is better to leave any lessons or remarks upon materials, 
tools, or manipulations, until the necessity occurs in the 
ordinary working of the room, or until required for com- 
parison. 

20 



J METAL-WORK 

SUBJECT : MAiaNG OF A FLAT CHISEL. 



Heads. 


Matter. 


Method. 


Object to be 


Fiat chisel. 


State this. 


made 






Use 


To cut other metals. 


Educe this. 




Therefore must be harder 


j> ? J 




than materials to be 






cut. 






Must be capable of taking 


S> ? J 




and retaining a fine, 






hard cutting edge- 




Material . . 


Selected cast-steel (tool 


State this, unless lesson 




steel). 


on cast-steel has been 
previously taken. 


Process of ma- 


Stock should not be cut 


Demonstrate and com- 


king 


off with cold set be- 


pare with iron, making 


o 


cause of brittle nature. 


a particular point of 
impressing upon pupils 
that great care and 
caution are necessary. 




Must either be filed or 


Demonstrate. 




heated and cut with 






hot set. 






Material must not be 


State this. 




heated above bright 






red, or the carbon 






would be burnt out. 






Must not be hammered 


Demonstrate. 




when cold, as this 






would cause it to split. 






Forge the point to a size 






slightly larger than 






finished size. 






Dress the head. 






Allow to cool off slowly. 


Demonstrate. 




because if jjlmiged in 






water it will be too 






hard to dress up. 






This slow cooling off is 


State meaning if not given 




called " annealing." 


in any previous lesson. 




Dress up with file or 


Educe this if cast-steel 




grinder to finish, and 


lesson has been given. 




also to remove any 


If not, explain and 




material deteriorated 


demonstrate* 




by loss of carbon in 






forging. 




Hardening and 


Hardness depends upon 




tempering 


rate of cooling from 






high temj)erature. 





NOTES OF LESSONS 307 

SUBJECT: MAKING OF A FLAT CHISEL— Continued. 



Heads. 


Matter. 


Ileihod. 


Hardening and 


If cooled slowly it is soft, 


Demonstrate. 


tempering — 


and if quickly, by plung- 




continued 


ing in water, it is hard. 






Very hard steel is too 


Show a chisel with this 




brittle for a cutting 


fault. 




chisel. 






But the tool must be 


Show efEect of iron on the 




harder than the ma- 


edge of a soft steel 




terial to be worked. 


chisel. 




Particular degrees can be 


Educe this by referring to 




obtained. 


hammers, hies, lathe 
tools, etc. 




Two methods of temper- 






ing are in common use : 






(a) Point hardening, 


Demonstrate. 




by heating j)oint 






only, cooling, rub- 






bing, and temper- 






ing. 






(&) Harden, and then 


Demonstrate, and educe 




draw the temper 


what happens. 




to required degree 






over Bunsen 


Compare results of a 




burner. 


and b. 




The latter is better, as it 






gives a more even 






temper. 




Colour scale . . 


Show the colours ob- 


As observed, make a list 




served on chisel b. 


of shades and colours. 
Draw list on blackboard 
with coloured chalk: 




^ 


Hard — grey. 

pale straw. 

dark straw. 

light purple. 

dark purple. 

dark blue. 
Soft — pale blue. 
Mark the colour at M^hich 
chisel is left. 




Blue is nearest the ap- 


Educe this. 




plied heat. 






Therefore softest. 


37 3 ? 




The required colour for 


State this. 




cold chisels is dark 






purple. 






The colours are a thin coat- 


State this. 




ing of oxides, and due 






to the action of the air. 






Do not penetrate the 


Demonstrate by rubbing 




metal. 


with emery- oloth. 



308 METAL-WORK 

The questions of illustrations, apparatus, and specimens, 
need careful thought. Illustrations when of a complicated 
nature should be prepared beforehand, but if simple may be 
drawn during the course of the lesson upon the blackboard by 
the teacher, or preferably by the pupils, if any possess the 
necessary knowledge. 

Apparatus, such as models, tools in process of manufacture, 
etc., should also be set up before and be read}^ to hand. 

Specimens of material, whenever possible, should be cui; 
from the common stock of the room, as boys sometimes 
attribute virtues to prepared specimens which they imagine 
do not exist in the material supplied to them. 

In demonstrating tool manipulations also, use the common 
tools, for the same reason. 

In all lessons try to bring out the essential points, and always 
remember there are facts which no amount of questioning will 
ever educe. These must be stated. 

Further, always try to point out or educe any characteristic 
which may be peculiar to the material or tool being dealt with, 
the annealmg properties of copper and brass, the peculiar 
method of annealing zmc, the inability to solder alummium, 
etc., and make any comparisons which will strengthen your 
statements. 

The blackboard summary is made as the lesson proceeds, 
and contains a condensed account of the facts in the " Matter "" 
column of the " Notes of Lessons."' Any sketches necessary 
are also made upon the blackboard. These have a great 
advantage over pictures or diagrams, in that the fact being 
dealt with may determine the scale of the sketch. It is also 
valuable, as it allows the pupils sometimes to make the 
sketches. This method develops keenness and encourages 
private research. 

As previously stated, the danger lies in the temptation to 
allow this summary to be copied into the notebooks. 



APPENDIX 

CITY AND GUILDS OF LONDON INSTITUTE 

EXAMINATIONS FOE TEACHEES' CEETIFICATES 

IN MANUAL TEAINING 



METAL-WORK. 
1913. 



FIBST YEAB. 



DE AWING (Three Hours). 

1. Top of Spindle of Drilling Machine and Supporting Lever 
{Fig. 1). — Draw a plan and elevation, and a section which is to 
be taken at the centre line AB. 

Scale, full size. (50 marks.) 

2. Bell Crank Lever for a Shaping Machine {Fig. 2).- — Draw the 
elevation, and a section which is to be taken as the centre line EF. 

Scale, full size. (50.) 



WEITTEN EXAMINATION (Three Hours). 

Instructions. 

All candidates must attempt Questions 2 and 5 or 6, and not 
more than five others. 

1. Pieces of copper, brass, cast-iron, and cast-steel, are each 
heated to a dull red colour, and immediately dropped into water 
at 32° F. What will be the effect upon each piece of metal 
beyond th^ reduction of its temperature ? (12 marks.) 

309 



310 



METAL-WORK 



2. How would you repair — (a) sl sprained spanner; (&) a burnt 
soldering iron; (c) a broken light chain sling for temporary but 
immediate use (a forge and tools for making a new link are not 
available); (d) a dull cutting screw-thread chaser; (e) a seized 
lathe head journal caused through neglect in lubrication '? (12.) 



Round Nuts Recessed, 
■^Wide ^Deep 

Hard Steel Washers 




Fig. 1. 



3. Distinguish clearly between annealing and tempering, case- 
hardening and chilling, and give examples of each case where 
ti^eatment of the metal under one or more of the processes is an 
essential (a) for effective working and manipulation, (fe) for re- 
sisting wear. (12.) 



EXAMINATION PAPERS 



311 



4. Suppose that three highly -polished pieces of metal, ap- 
parently iron, were given you to distinguish and name at sight. 
Describe what test or tests you will afterwards apply to each 
specimen to prove whether you have named the material cor- 
rectly. (12.) 

5. Sketch and describe some simple recording apparatus which 
will assist your boys to realize quickly the relative expansion of 
the metals most commonly used in the metal-work room. (14.) 




F 



Fig. 2. 

6. How would you set about doing the following soldering jobs, 
n consecutive order, so as to demonstrate clearly the use of the 

blowpipe flame, soldering bit, solder paste, and fluxes: to unite 
{a) two pieces of zinc; (b) two strips of sheet steel | inch wide, 
1 inch thick, to form a right-angle piece 4 inches long; (c) two 
pieces of 9-pound copper sheet, 3i inches square, so as to double 
the thickness of the metal? Terse details of procedure are 
required. (14.) 

7. The following terms have special reference to work or 
operations involved in a course of metal-work for first-year 



312 METAL-WORK 

scholars: "calibrating," "fuller," "spelter," "backing ofP," 
" angle of relief," " banking up." Grive a clear definition of each 
term. (12.) 

8. You are asked by one of your scholars to " explain for the 
benefit of his class " the working of an acetylene lamp. Recount 
the answer given, and illustrate with sketches the general prin- 
ciple involved, and how such can be fully demonstrated by means 
of simple and readily- obtainable material. (12.) 

9. What do you understand by the term " mechanical effi- 
ciency " ? Give a simple description of the principle of " thp 
screw." A screw having six threads per inch, under certain cir- 
cumstances, has a mechanical advantage of 286. Find the 
greatest diameter of the track made by the " tommy " used to 
actuate the screw. (12.) 

10. Give sketches of the tools and appliances used in making 
a hollow casting of metal in an ordinary casting-box, showing 
the latter clearly in vertical section, to include the cope, drag, and 
moulding board, with core, runner, vent, and feeding head, com- 
plete in detail. (14.) 



PRACTICAL EXAMINATION (Four Hours). 

Work Test A and either B or C. 

A. The drawing shows the front and side elevation of a pyram- 
idal tube constructed from one piece of tinplate. You are re- 
quired to set out the full development on the sheet of cartridge 
paper supplied, cut out the pattern, and use it for the " lay out " 
of the metal. All lap joints must be arranged within the tube. 
{Fifty per cent, of the maximum marks obtainable will be deducted 
if the work is sent in without the paper pattern, together with the 
sheet of cartridge paper from which it was cut.) (60 marks.) 

B. The drawing shows a three-way junction tube. Construct 
this from the length of tubing supplied, using any method of 
jointing you like which will give a clear bore throughout. (40.) 

C. Construct — i.e., forge, harden, and temper — the pocket- 
scriber reprd33nted to the dimensions given. (30.) 



EXAMINATION PAPERS 



313 




U- 2C 



FiG. 3. 



FINAL. 



PEACTICAL EXAMINATION. 

First Day (Four Hours.) 

You are supplied with sufficient material to construct the 
smoker's ash-tray, inkstand, or fern-pot holder, in accordance 
with the dimensions given on the outline sketches. Make it. 
(100 marks.) 



Second Day (Four Hours.) 

Material is supplied for the construction of a " quick return 
motion " model. The drawings show the elevation and end view 
of the finished object mounted on a base plate. 

You are required (1) to complete the essential details of move- 
ment so that the model will work ; (2) to show your idea of " finish" 
on any one of the details; (3) to add any other detail which, in 
your opinion, would make this model of more educational value 
for giving a demonstration of speed movement. [For (1), 100 
marks; for (2), 25 marks; for (3), 25 marks.] 



314 



METAL-WORK 

" g' square 




Plan of 
Top Piece. 



SECTION ON A.B 



Sketch of Inkstand 
and Tray, 



Fig. 4. 



DRAWING- (Three Hours). 

Hand Drilling Machine. 

Draw a section of all the parts of the drilling machine 
between the breast -piece P and the end AB of the frame, the 
section to be taken at the centre line CD. Do not draw the 
piece marked P. Arrange for the pin on the wheel Wj to fit 
in either of the holes H^ or Hg, and to gear with portions of the 
wheel W2. 

Draw an elevation of the same parts of the drilling machine 
when looking in the direction of the arrow K. Do not draw the 
details of the teeth of the wheels in elevation. Scale, full size. 
(100 marks.) 



EXAMINATION PAPERS 



315 



i, te 



-^^- 



-^ — I — S Q 



uxu 



r 




6 

M 



316 



METAL-WORK 







CO 

2 



EXAMINATION PAPERS 317 



WKITTEN EXAMINATION (Four Hours.) 

Part I. 
Not more than four questions to he attemjpted in Tart I. 

1. Give diagrammatic sketches of the Otto cycle as applied 
to a petrol motor, showing very clearly the positions of the re- 
spective inlet and exhaust valves at each period, and briefly 
describe — as in answer to a boy's question, " How does a motor 
work "?" — the work done during the complete cycle. 

2. Name the metals or alloys which you would adopt in order 
of preference in supplementing the knowledge gained by senior 
boys during a full course of laboratory work in physics and 
chemistry, and to correlate efficiently the practical work of simple 
apparatus making. Grive sketches of any two pieces of simple 
apparatus constructed from any of the metals or alloys named 
which will serve to demonstrate clearly {a) a principle of me- 
chanics; (6) an occurrence in Nature, or transmission of motion 
or power. 

3. Give a sectional sketch of a small forge blower or fan, indi- 
cating clearly the method of driving by hand-power, and the con- 
nection with the " tuyere " or " tue iron." 

4. Classify the following metals and alloys according as they 
may be {a) forged, {h) soldered, (c) cast: Lead, mild-steel, copper, 
bismuth, tin, brass, wrought-iron, cast-iron, aluminium, zinc, and 
silver ; and place each in order of heat-conducting power. 

5. A right-hand screw of ten threads per inch is to be cut in a 
l^the which has a leading screw of f inch pitch. Sketch the train 
of wheels necessary, give the number of teeth in each, and clearly 
show what alteration would be necessary to cut a left-hand 
thread on the same lathe. 

6. In reply to a boy's question, " How does a lever lock 
work f ' you would be required to give a few good sketches of 
the internal mechanism of some type of multiple tumbler or pin 
piston action, accompanied by some simple explanatory matter 
concerning each detail. Kecount fully the reply given, making 
your sketches at least double full size, in order to add clearness 
of detail and reference. 



318 METAL-WORK 

7. Light metal-work is gradually being introduced into the 
ordinary courses of wood-work. Give three sketches of models 
which will clearly show advantages obtained by judicious com- 
bination of the media, as to (a) strength, (6) embellishment, 
(c) general utility. 



Part II. 



1 



Question 8 to he attempted by all Candidates, and not more than 
three others in Part II. 

8. Describe how you would give a lesson on any one of the 
following subjects: 

(a) Case hardening. 

(b) How to produce a plane surface. 

(c) The making of a screw-thread (1) by hand-chasers, (2) by 

change-wheels. 

9. What special value do you claim for metal-work as part 
of a complete course of manual training *? 

10. You are asked to co-operate with the science teacher of a 
school in framing a practical course in either mechanics or elec- 
tricity and magnetism. Give your ideas about the way to make 
this co-operation as effective as possible, from the point of view 
both of your own work and of that of the teacher of science. 

11. Give examples of the difficulties in teaching metal-work 
which arise from differences in the speed and quality of work 
of different pupils in the same class. Show how you would deal 
with these difficulties. 

12. Some exercises in handwork are technical exercises — that 
is, they are intended to familiarize the pupil with an operation 
or a tool to be used later in constructing an object which is re- 
quired for its own sake. Give illustrations of such technical 
exercises in metal-work, and of the methods which you would 
follow in order to make them effective. 

13. " Proceed from the known to the unknown." Show how 
you would apply this principle of teaching (a) at the beginning of 
a course of metal-work; (b) in the later stages of the course. 



EXAMINATION PAPERS 



319 



METAL-WORK. 

1914. 



FinST YEAE. 



DRAWING (Three Hours). 

1. Tin Vase {Fig. 1). — Draw full size the elevation of the tin 
vase shown in Fig. 1. Every horizontal section of the vase is 
square. Draw the development of the vase with the bottom and 
the laps for the joints, when unfolded in one plane sheet. Write 
on the development, which are inside and which outside laps. 
(25 marks.) 




I 
Fig. 1. 



2. Draw an isometric view of the vase given in Fig. 1. 
Scale, full size. (10.) 

3. Make a good freehand sketch from memory of some piece of 
bent ironwork, preferably a sketch of something you have made. 
It must be carefully drawn, and should not take more than 20 to 
30 minutes. (15.) 

4. Small Crank Disc, Pin, and Connecting Bod {Fig. 2).— The 
mechanism shown in Fig. 2 is used to convert the circular motion 



320 



METAL-WORK 



of vertical spindle and crank disc into the reciprocating motion of 
the plate P, which moves in the line EF. How can the travel of 
the plate P be altered in length "? Instead of the elevation, draw 
a section taken at the line EF. Draw the plan and the end view. 
Scale, full size. (50.) 




Fig. 2. 



WEITTEN EXAMINATION (Three Hours). 

Instructions. 

Candidates must attempt Questions 2 and 5 or 6, and not 
more than eight questions in all are to be answered. 



1. Give a concise definition of each of the following terms, 
which are chiefly used in correlating a course of metal-work with 
a science course in a school laboratory: " angle of friction," 
" angular velocity," " Barker's mill," " Beaumontague," "heat 
unit," " stress." 

2. Distinguish clearly between positive and non-positive 
motions, giving examples of each, {a) having reference to types of 
machines usually found in a fully- equipped metal- work centre, 
(&) to road traction machines and other transport conveyances. 



EXAMINATION PAPERS 321 

3. Design and sketch any simple apparatus which would assist 
your pupils to realize that a screw-thread is a helix, which, if 
further analyzed, is found to be an inclined plane." 

4. A vertical cylinder, 3 inches diameter and 5 feet high, is 
pierced by another cylinder l^ inches diameter at an angle of 
45 degrees to the base; the latter cylinder is cut off flush with the 
top and bottom of the vertical cylinder, and therefore also has 
a vertical height of 5 inches when in position. Draw the develop- 
ment of this geometric model. 

5. Give brief details of procedure such as would guide your 
boys to make fair jobs of the following tests: {a) The preparation 
of a true surface; (6) making a pair of outside callipers; (c) making 
a trinket-box, oblong in form, with raised lid. 

6. The following repairs require immediate attention: 

{a) One of the treadle-board levers of a foot-lathe is broken 
midway between the board and the rocking shaft* 
The cross-section of the lever is T-shaped. 

(6) The pawl of an enclosed ratchet brace refuses to act 
when resistance has to be overcome. 

(c) The jaws of a leg vice refuse to grip thin plate, and re- 
cutting is not possible. 
Detail your method for effecting these repairs. 

7. Why is it necessary to use a flux when joining two metals 
permanently together '? What would you suggest as suitable 
flux for — {a) making a joint on a piece of " compo " pipe; {b) sol- 
dering up a model made from sheet zinc; (c) making a T-joint 
on a length of electric light wire; {d) welding cast-steel '? 

Patent composition fluxes are not available. 

8. Enumerate and discuss the essentials to be given in detail, 
for notebook reference, to a class of first-year boys before com- 
mencing a lesson in forging. State reasons for your method of 
procedure. 

9. You are asked by one of your scholars to explain to the class 
" the working of the fan which produces a continuous volume of 
air for the forge fire." Kecount the answer you would give, and 
illustrate with sketches to show the essential difference between 
bellows and fan action, and how the principle of continuous 
pressure of vapour or air under compression can be demonstrated 
by simple and inexpensive working toy models which are within 
the range of a light metal-work equipment. 

21 



3^2 



METAL-WORK 



10. How would you explain tliis statement — " The specific 
gravity of iron is 7' 4, and the relative density of sheet copper is a; 
8-8"? 1' 

Sketch any simple apparatus, which could be made by your 
boys, to prove the statements you may make in reply to the 
query, " If iron sinks, why does an iron ship float V 




PEACTICAL EXAMINATION (Four Hours). 

Work either of the two problems A or B. 

A. The drawing (Fig. 3) shows the front elevation and plan df 
a trinket-box, with raised lid, hinged or not as you may determine. 
The box is supported as shown; the design of the elevation may 




Plan at a. 

Fig. 3. 







w 



Fig. 4. 



be varied, but the plan must be adhered to. All joints are to be 
butt-soldered. (100 marks.) 

B. From the piece of mild-steel supplied, make the double- 
ended spanner to the dimensions given (Fig. 4). On the paper 



EXAMINATION PAPERS 323 

supplied state clearly the procedure you adopted to remove the waste 
material, naming the hand-tools or machines used during the opera- 
tion. Unless this information is given, the award of marks will 
be reduced by 50 per cent. Candidates must take care, there- 
fore, to write on the paper their examination number as on their 
card, and to place the paper with their practical work at the end 
of the examination. (100.) 



FINAL. 



DRAWING (Three Hours). 

1. Driving Gear for Morlising Machine: 

An elevation of the machine is given. In the end view and plan, 
the pulley, horizontal spindle, and bevel wheels, are omitted. 

Motion is transmitted from the pulley and horizontal spindle 
through two bevel wheels to the vertical spindle and crank disc. 

The reciprocating motion of the mortising tool is taken from 
the crank disc by means of rods and pins not shown on the 
drawing. 

Draw, to a scale of half full size, omitting the bevel wheels — 
{a) A sectional elevation, the section to be taken at the line 
AB; and 

(b) A sectional plan, he section to be taken at the line CD. 

(60 marks.) 

2. In addition, either — 

(c) Draw an end view looking in the direction of the arrow 

K to a scale of half full size ; and {d) draw, separately 
from the rest of the drawing, a section of the bevel 
wheels in gear, to a scale of full size, the section to be 
taken at the line AB. (40.) 



or- 



Design and draw the lamp bracket shown in Fig. G to a 
full-size scale. In the interior of the triaugle draw 
two scrolls of bent-iron work, as suggested in the 
sketch. Show clearly on your drawing some means of 
fixing the parts of the bracket together. (40.) 




4' screw 
Nwt 






Fig. 6. 



EXAMINATION PAPERS 325 

WEITTEN EXAMINATION (Four Hours). 

Part I. 

Not more than four questions to be attempted in Part I. 

1. " Metal- work of a mere elementary character, involving only 
a few simple tools and much, lighter metals, is being advised as 
more suitable for boys of twelve to fourteen years of age who 
are in attendance at elementary or secondary schools." Briefly 
discuss this statement, and indicate what craftsmanship on the 
part of the teacher you would consider essential for efficient 
instruction, and what should be the basis and ultimate aim of 
any teaching of this character. 

2. You are required to connect up with belting a small forge 
fan. The main shaft runs at 120 revolutions per minute, and a 
pulley 3 feet 4 inches diameter is available. The pulley on the 
fan shaft is 2^ inches diameter, and for high efficiency the fan 
must run at 4,000 revolutions per minute. Sketch the arrange- 
ment you suggest, and draw up a short specification from which 
any other gear you may require — i.e., pulleys, countershaft, 
brackets, starting lever, etc. — may be ordered. 

3. Outline the procedure you would follow in giving demonstra- 
tion lessons on [a) a first lesson in hand-turning on a treadle 
lathe; (&) the boring and tapping of a piece of cast-iron plate; 
(c) the " finish " — i.e., cleaning, burnishing, and lacquering— of 
a piece of beaten- copper work. 

4. During a certain term lessons on moments, triangle and 
polygon of forces are being given by the science class teacher. 
What special apparatus (capable of being constructed entirely by 
the boys receiving these lessons) would you propose to make to 
give direct application of the principles involved ? Grive sketches 
of proposed apparatus, stating materials and tools required. 

5. What would you consider a fair equipment for — 

{a) A medium metal- work centre, established with a view 
to correlate with the work done in the science 
laboratory of a secondary school; 

(b) A metal and wood work combination (metal-work tools 
only required) ;] ^ 

'^(c)jA light metal-work course taken in an ordinary class- 
room 1 



326 METAL-WORK 

6. Briefly detail the procedure followed in making iron, mild- 
steel, brass, cast-steel, and a copper alloy capable of being forged 
bot. The information asked for is such as you would give in reply 
to a boy's question bearing upon manufacture of metals. 

7. Give details of five methods of permanently joining metals, 
and five methods of doing the same semi-perm anently. Glive 
sketches of the latter methods. 



Pakt II. 

Question 8 is to he attempted by all Candidates, and not more than 
three others in Part II. 

8. " Teaching and learning cannot be effective unless they are 
guided by a purpose clearly indicated by the teacher and genuinely 
adoi)ted by the learner." Give illustrations of this principle in 
connection with (i.) a demonstration lesson and (ii.) a practical 
exercise. 

9. Show by examples that it is sometimes profitable to permit 
your pupils to make mistakes, and sometimes important to prevent 
them from doing so. 

10. Give an account of the most important uses of the black- 
board in teaching metal-work. 

11. Show by examples how observations made by his pupils 
outside the workshop may be utilized by the teacher of metal- 
work. What steps would you take to encourage systematic and 
profitable observations of this kind 1 

12. A course of simple lessons on the chemistry and physics 
of the metals is to be arranged for a class taking metal work. 
State briefly what you think such a course should include, and 
indicate how it might usefully be co-ordinated with the lessons 
of the workshop. 

13. What kinds oi notes should be kept by pupils at different 
stages of a course of metal-work '? By what means would you 
encourage neatness, independence, and intelligence, in note- 
taking 1 



EXAMINATION PAPERS 



327 



PRACTICAL EXAMINATION. 

First Day (Four Hours). 

You are required to construct the lamp bracket to the dimen- 
sions given on the outline sketch furnished. 

Note. — The jointing may be either by rivets or soft sol- 
dering, except where the curves are attached to the tube at 
A and B, when the given bolts are to be used. 




h- 






Fig. 7. 



All holes (other than in the tube) may be punched after 
the curves are formed. Where two curves overlap, the 
smaller one should be thinned down or scarfed to fit neatly, 
then soft soldered and riveted. 



328 METAL-WORK 

The material is supplied in lengths as follows : 

24 inches, to make the sides and base curves of the holder. 
17| inches, to make the tension bar and upper curve C. 
15 inches, to make the two circles for the holder. 
Two 14| inch lengths, to make the lower curve D and the 
remaining tendril curves. 

It is essential that the worJc shall he done in the following sequence : 

1. Lamp-holder and tube. Attach these to back piece. 
(60 marks.) 

2. Tension bar and upper curves and tendril. Attach these to 
lamp-holder, tube, and back piece. (20.) 

3. Lower curve and tendrils. Attach these to tube and back 
piece. (20.) 



Second Day (Four Hours). 

You are required to construct the model of a variable radius 
lever to the dimensions given on the sketches (Fig. 8). 

Note. — The crank support and the crank are supplied in 
one casting; from this prepare the two items for free move- 
ment. 

Any holes (tapped or otherwise) which may be in the 
casting may be utilized, if convenient. 

The connecting links may be riveted together, or any other 
suitable means adopted to retain them on the slider nut 
trunnions. 

The small bearing bracket into wliich fits the casting of 
the radius lever is to be built up or constructed from the 
sheet brass provided, with the ^g-inch cheese-head screw 
used as the bearing pin. 

It is essential that the work shall he done in the following sequence : 

1. Complete the radius link A in detail. (60 marks.) 

2. Make bearing bracket and connecting links. (20.) 

3. Make the crank support B, the crank C, and the crank \ 

pin. i(20.) 

4. Assemble the details^ and attach to the wood base ) 



EXAMINATION PAPERS 



329 




h-l 




GLOSSARY OF TECHNICAL TERMS USED IN 
SCHOOL METAL-WORK 

Abrasion — act of rubbing away. 

Alluvia — muddy deposit. 

Amalgams — alloys containing mercury. 

Annealing — softening of metals. • 

Anode — electric positive pole. 

Apron — front of saddle in screw-cutting lathe. 

Aqua-fortis — nitric acid. 

Aqua-regia — mixture of nitric and hydrochloric acids, capable of dissolving 

the noble metals. 
Arbor — main axis of a piece of mechanism. 
Arc of contact — surface of pulley in contact with belt. 
Argillaceous — in the nature of clay. 

Backlash — slacking between teeth of cog-wheels. 

Banking up — covering of fire with fuel. 

Bauxite — ore of aluminium, from Baux, in France. 

Bellied — used to describe fulness in centre of sheets, etc. 

Blind hole — hole not passing through material. 

Blooms — wrought-iron when collected from puddling furnace. 

Blue-billy — purple ore from which sulphur and copper have been extracted. 

Boshes — portion of blast furnace immediately above hearth. Alternative 

name for cooling tank. 
Boss — protuberance in metal. 
Broach — reamer; tapered boring drill. 
B.T.U.— British thermal unit. — Heat measure. Heat necessary to raise 

1 pomid of water 1° F. = one B.T.U. 
Bulldog — roasted tap cuider, sometimes used for fettling. 
Burr — rough ridge left on metal after cuttmg. 

Calibrate — to test internal sizes. 

Cathode — electric negative pole. 

Cinder — refuse of furnace after combustion. 

Clinker — forge cinder. 

Cohesion— force uniting two particles of same nature. 

Cold-shortness — brittleness in metal when cold. 

Compo — alloy of lead and tin used in pipe-making. 

Cope — top box of a pair of casting boxes. 

Core— material used for forming the hollow parts in castings, as in pipes, 

cylinders, etc. 
Cry — cracking noise made in tin when bent. 
Cryolite — ore of aluminium. 
Cupola — small blast furnace used in iron casting. 

330 



GLOSSARY OF TECHNICAL TERMS 331 

Dolomite — -carbonates of limo and magnesia used in lining the basic 

Bessemer converter. 
Doubles — tinplate twice dipped in tin. 
Drag — bottom box of a pair of casting boxes. 

Dra!wbacks — arrangement for allowing patterns to leave the sand mould. 
Drift — punch for loosening keys. 

Energy — force supiDlied to machines. 

Fettling — bottoming used in furnaces. 

Float — single cut file. 

Flux — substance to remove oxides from metal, or to assist flowing. 

Freezing — solidifying of metals. 

Galvanize — coating iron with zinc. 

Gangue — earthy matter in metallic ores. 

Gannister— hard sandstone used for lining acid Bessemer converter. 

Graphite — form of black carbon. 

Grub-screw — small, headless screw with a slot for turning. 

Homogeneous — of same nature throughout. 

Horse-power — 33,000 pounds raised 1 foot in one minute = one horse-power; 

usually written H.P. 
Hydrocarbons — compound of hydrogen and carbon, such as oil. 

Intermittent feed — ceasing or relaxing at intervals, as self-acting motion in 
shaping and drilling machines. 

Jenny — odd-legged callipers, used for marking lines parallel to edges. 
Jig — template to locate position for drilling holes. 

Kink — swan neck or double bond. 

Lay-out — development. 

Lodes — regular metallic veins. 

Loose-metal — excess of metal which causes bellying in sheets. 

Mandril— axis upon which work is placed to be turned. The chief axis of 

a machine. 
Matting — grounding used in repousse. 
Mechanical advantage— apparent exaggeration of power as illustrated in the 

lover, screw, incline plane, pulley block, etc. 
Mine (puddlers)— bottoming used in puddling furnace. Sometimes called 

"fettling.'' . . 

Molecules— smallest quantity of an element or compound that can exist m 

the free state. 

Native— term applied to metals found in a pure state. 

Non-positive motion— driving by belts or friction clutches, in which slippmg 
is possible. 

Out-crop — mineral vein appearing on the surface. 
Over cut — first series of cuts in file-making. 



332 METAL-WORK 

Particle — minute part or portion. 

Pawl— pivotted bar used either to prevent recoil or to apply power to a 

ratchet. 
Pickle — mixture of acids used for cleaning metals, or for removing the hard 

skin from castings. 
Pitch — one thread and one hollow of a screw, or the distance between two 

rivets or screws. 
Placers — ores in a muddy deposit. 

Plumbago — form of carbon, used in the manufacture of crucibles. 
Pockets — large holes or cavities filled with metallic ore. 
Poling — ^removing oxides by stirring with wood in final refining of copper 

and tin. 
Positive drive — driving through toothed wheels or connecting rods in which 

no slipping is possible. 
Power — energy developed by engine or machine. , 

Puddlers' candles — small flames which appear during puddling. 
Puddlers' mine — bottoming used in puddling furnace. 

Rake — relief or clearance angle of cutting tools. 

Ratchet — bar or wheel with angular notches to accommodate a pawl. 

Red-shortness — brittleness when hot. 

Rust — oxides. 

Spelter— solder used for brazing. Commercial term for zinc in bulk. 
Spirit — common term for zinc chloride. 
Spirit of salts — common term for hydrochloric acid. 

S.S.G. — standard sheet gauge, used for measuring thickness of sheet metal. 
Staggered — out of straight. 

Strain — force acting on any material and tending to disarrange its com- 
ponent parts. 
Streaming — method of removing earthy matter from ores by running water. 
Stress — force exerted in any direction or manner on bodies. 
Stroke — piston travel in engines and travel of tool in shaping machines. 

Template — pattern to mark off or define the shape of work. 

Three-square — term used to define a file whose section is an equilateral 

triangle. 
Throw — -distance between centre of crank and crank- shaft. Distance 

between centres of an eccentric. 
Tough pitch — restoring elasticity to copper or other alloy metals. 
Trunnion — hollow axle, as instanced in the Bessemer converter. 
Tuyeres — openings through which forced blast enters furnaces or forges. 

Up-cut — second series of cuts in file manufacture. 

Viscosity — stickiness. 
Vitriol — sulphuric acid. 

Work — result of energy in a machine. 

Z.G. — zinc gauge. System of denoting thicknesses of zinc. 



INDEX 



Alloy metals, manufacture of, 46 
Alloying, effects of, 65 
Alloys, 60 

(copper-tin), 62 
(copper-zinc), 61 
(standard), 63 
preparation of, 66 
(tin-lead), 63 
Aluminium, 57 

,, furnace, 58 

,, ore, 13 

,, properties and charac- 

teristics, 74 
Annealing, 153 
Anvil, 143 

,, stand, 143 

Basic process of steel-making, 33 
Bauxite, 58 
Beds, 8 

Bessemer, basic process, 33 
,, converter, 29 
„ general arrangement, 30 
„ general process, 28 
„ method of conducting 
blow, 31 
Blackband ironstone, 11 
Black-Jack, 12 
Blast-furnace, 19 

,, history of, 16 

,, reactions, 22 

Blende, 12 
Blister- steel, 41 
Brass, high, 62 
,, low, 62 
,, properties, 73 
Brazing, 125, 137 

,, process, 139 
Bronzing, 212 
Bunches, ore, 8 



Calcination, 17 
Calcinator, 18 
Callipers, 100 
Carriers, 193 
Case-hardening, 156 
Cassiterite, 13 
Casting, 171 

,, burning on of broken, 176 

,, section of boxes, 174 
Cast-iron, 15 

,, manufacture, 15 

,, properties and cl .,i.-acter- 
istics, 67 
Cast-steel, blister, 41 

„ cementation process, 39 

,, crucible, 40, 42 

,, grades of, 44 

,, manufacture of, 39 

,, properties and character- 

istics, 69 

,, puddled, 45 

,, self -hardening, 44 

,, Wootz, 45 

Cementation furnace, 40 
Centering square, 192 
Centre punch, 99 

„ (bell), 99 
Change- wheels, 199 
Chemical properties of metals, 6 
Chisels, 110 
Chucks, drill, 195 

,, lathe, 193 
City and Guilds Examination Papers 

(1913), 309 
City and Guilds Examination Papers 

(1914), 319 
Clamps, 82 

Clearance angles of lathe tools, 197 
Cohesion, 3 
Cold shortness, 27 



333 



334 



METAL-WORK 



Combined work, suggestions for, 271 
Conductivity of metals, 5 
Copper, 11, 46 

,, analysis of, 12 

,, blast-furnace, 48 

,, furnace, 47 

,, ore, 12 

„ properties and characteris 
tics, 70 

„ smelting districts, 12 

,, source of supply, 12 
Countershafting, 217 
Crucible steel furnace, 43 
Cupola, 171 

Dividers, 101 
Drawing, 295 
Drilling, 157 

,, machines, 161 
Drills, 158 
Ductility of metals, 3 

Electric motor, 236 

Electrical conductivity of metals, 5 

Engraving, 208 

Equipment of workshop, 241 

Feeds for tools, 216 
Files, 84 

,, cut, 85 

,, length, 84 

„ manufacture, 88 

,, sectional forms, 85 
Filing, 89 
Finery furnace, 24 
Finishing and polishing, 211 
Flatter, 145 

Flintshire lead furnace, 51 
Fluxes for brazing, 138 

„ for sheet metals, 135 
Forge, 141 

„ tongs, 146 

„ work, 140 

„ „ primary operations, 

147 

„ ,, secondary operations, 

148 

„ ,, various operations, 149 

Fullers, top and bottom, 145 

Galvanizing, 13, 72 
Gangue, 7 
Gas-engine, 233 
Gauges, standard, 223 



Glossary, 330 , 

Gravels, 8 

Grinding, 169 

Grindstones and grinders, 169 

Haematite, brown, 10 

,, red, 9 

Hammers, 107 

,, repousse, 108 

,, sledge-, 108 

,, tinplate, 108 
Handicraft, term, 287 
Hardening and tempering, 153 
Hardie, 145 . 

Hardness of metals, 4 
Heat conductivity, 5 

Iron pyrites, 11 

Lacquering, 213 
Lathes, 177 

,, care and testing of, 203 
,, carriers, 193 
,, change- wheels, 199 
,, clearance angle of tools, 197 
,, names of parts, 178 
,, plain, 177 
,, screw-cutting, 183 
,, tool-holders, 197 
,, tools, 196 
„ work, 177 
Lead, 12, 51 

,, Flintshire furnace, 51 

,, ore, 12 

,, properties and characteristics, 

74 
,, slag- hearth, 53 
,, source of supply, 12 
Lodes, 8 

Magnetic ore, 10 
Mallets, egg-ended, 107 

,, flat-faced, 106 
Manual instruction, use of term, 286 

,, training, use of term, 287 
Materials, cost, 228 
,, sizes of, 226 
weights, 228 
Metals, conductivity, 5 

,, discovery of, 1 

,, ductility, 3 

,, fusibility, 4 

,, hardness, 4 

,, malleability, 2 



INDEX 



335 



Metals, occurrence in Nature, 7 
,, properties and characteris- 
tics, 167 
,, specific gravity, 2 
,, strength, 6 
,, table of tests, 75 
,, tenacity, 3 
„ weight, 1 
,, workshop uses, 67 
Mild-steel, characteristics and prop- 
erties, 69 
,, manufacture, 28 
Moh's scale of hardness, 4 
Motor, electric, 236 

Notes of lessons, 301 
Nuts, formula for, 220 

Oil-motor, 233 
Ores, beds, 8 

,, brown haematite, 10 

,, bunches, 8 

,, forms of, 8 

,, gravels, 8 

,, iron pyrites, 11 

,, lodes, 8 

,, magnetic, 10 

,, pockets, 8 

,, red haematite, 9 

,, spathic, 10 

,, veins, 8 

Petrol-engine, 235 
Pig-iron, grey, 21 
„ mottled, 22 
,, white, 21 
Pitch of screw-threads, 223 

,, of rivets, 165 
Pliers, 112 
Pockets of ores, 8 
Polishing and finishing, 211 
Power, motive, 230 

,, to drive machine tools, 217 
,, to drive shafting, 217 
Puddling furnace, 25 
,, process, 25 
Punches, round and square, 146 
Punching, 152 

,, machines, 167 
Pyrites, copper, 12 
,, iron, 11 

Hepousse work, 205 
Rivets, 164 



Rivets, formula, 166 

,, heads, 164 

,, set, 166 
Rule, 96 

Saws, hack, 115 

,, piercing, 115 
Scheme of work, combined, 271 

,, ,, metal, 249 

Scraper edges, 93 
Scraping, 93 
Screw-cutting, 199 
Screw-plate, 122 
Scriber, 98 
Scribing block, 104 
Sets, 144 
Shafting, 217 
Shearing machine, 169 
Sheet metal work, 125 
Siemens' regenerative furnace, 34 
Sizes of materials, 226 
Slojd, use of term, 287 
Soldering, 125 

bits, 132 
fluxes, 135, 138 
hard, 137 
process, 136 
silver, 139 
soft, 132 
stoves, 132 
Solders, composition of, 136, 138 
Spanners, 114 
Spathic ore, 10 
Speeds and feeds, 215 
Spelter, brazing, 138 
Spiegeleisen, use of, 38 
Standard threads, 219 
Steam-engine, 231 

,, ,, slide valve, 232 
Steel, basic open-hearth process, 36 
,, basic process, 33 
,, cast-, 39 
„ mild, 28, 69 
,, Siemens-Martin process, 35 
,, Siemens open-hearth process, 

34 
,, Talbot process, 36 
Stocks and dies, 122 
Stream-tin, 13 
Sulphide galena, 12 
Surface plate, 102 
Swage block, 144 
Swages, 145 
Sweating, 137 



336 



METAL-WORK 



Tap wrench, 121 
Taps, 118 

,, section of,' 120 
Teaching methods, 286 
Tempering, 153 

,, table, 155 

Tenacity of metals, 3 
Tensile strength of metals, 4 
Threads, drawings, 222 

,, pitches, 221 

,, standards, 219 
Tin manufacture, 53 
,, properties and characteristics, 

73 
,, source of supply, 13 
Tinning of soldering bit, 134 
Tinplate, joints, 131 

„ tools, 126 

„ wiring, 129 

,, working, 125 
Tools, cost of, 243 
Try-square, 97 
Turning, lathe, 198 
Tuyere, dry, 140 
„ wet, 140 

Vee blocks, 105 
Veins, 8 



VeinstufP, 7 
Vice clamps, 82 
Vices, 77 

,, hand-, 82 

„ leg-, 78 

,, parallel, 78 

Washers, formula for, 220 

Welding, 150 

Wire-drawing, 3 

Wiring tinplate, 129 

Work, schemes of, 249 

Wrought-iron, composition of, 26 
,, manufacture, 23 

,, market qualities, 26 

,, properties and char- 

acteristics, 68 



Zinc, 12 



Belgian method, 56 
characteristics and properties, 

71 
distillation furnace, 56 
manufacture, 55 
ore, 12 
retort, 56 

Silesian method, 57 
source of supply, 13 



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